1 ' .

I

MASTl I . .

QUARTERLY REPORT GENERL C+ISTRY DIVISIOI

October through De( I

< I ' Scientific Ed i to r : I

mber 1979

E. Harrar . . \

General Edi tor : C. 1. Talaber (I

I * ' , February 15, -980

he he

:e

This is an informal report intended primarily for internal or limited external distribution. opinions and condusiom stated are those of the author and may or may not be those 01 Laboratory. Work performed under the auspices of the U.S. Department of Energy by the Lawn Livermore Laboratory under Contract W-7405-Eng-48.

E

! -

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

.

CONTENTS

A n a l y t i c a l Research and Development f o r t h e Nuclear Explosives Programs . . . . . . . . . . . . . . . . 1

Hyphenated Ins t rumen t s Development . . . . . . . . . . . . 1

Improved I n l e t for Q u a n t i t a t i v e Mass Spectrometry . . . . . . . 9

Analyses of Fluorocarbon FC-86 with t h e G a s Chromatograph-Mass Spectrometer . . . . . . . . . . . . 11 Far - In f ra red Laser Development . . . . . . . . . . . . . 1 4

Pho toe lec t rochemis t ry . . . . . . . . . . . . . . . . Contamination S t u d i e s for t h e Weapons Development Program . . . . . . . . . . . . . . . . . 2 1

P o t e n t i o m e t r i c Study of Some Anions with Quaternary Ammonium Halides . . . . . . . . . . . . . . . . . . 25

A n a l y t i c a l Research and Development f o r t h e Energy Programs . . . . . 28

A u t o m a t e d , Portable, On-Line Mass Spectrometer for t h e Oil-Shale Program . . . . . . . . . . . . . . . . 28

F i e l d Tests of Organic Add i t ives f o r t h e Con t ro l of S c a l i n g of Hypersal ine Geothermal Br ine . . . . . . . . . . . . . 30

iii

GENERAL CHEMISTRY DIVISION QUARTERLY REPORT

ANALYTICAL RESEARCH AND DEVELOPMENT FOR THE

NUCLEAR EXPLOSIVES PROGRAMS

Hyphenated Instruments Development

Responsible Personnel: R. W. Crawford, T. B. H i r sch fe ld , C. M. Wong, R. H.

Sanborn, and R. G. Meisenheimer.

B r i e f Desc r ip t ion : Modern a n a l y t i c a l i n s t rumen t s are f a s t , precise, and

employ t h e power of computers, bu t o f t e n t h e results

from a s i n g l e instrument are ambiguous. We are

at tempting to wed s e v e r a l i n s t rumen t s i n real time to

i n c r e a s e t h e r e l i a b i l i t y of a n a l y s i s . I n i t i a l

experiments w i l l test gas chromatography (GC) as an

i n p u t to fast-Fourier- t ransform i n f r a r e d (FTIR) and

mass spectrometry, e i t h e r i n series or paral le l .

,+%--===---,--.--

Sta tus : Advances i n i n s t rumen ta t ion and the i n c o r p o r a t i o n of powerful

computers have c r e a t e d some remarkable a n a l y t i c a l tools. One of t h e most

powerful instruments i n the realm of o r g a n i c q u a l i t a t i v e and q u a n t i t a t i v e

a n a l y s i s is the computerized gas chromatograph-mass spectrometer (GC-MS).

This in s t rumen t combines t h e ou t s t and ing s e p a r a t o r y p r o p e r t i e s of t h e capillary chromatographic column with the fast and sensitive fingerprinting

c a p a b i l i t y of t h e mass spectrometer . The computer allows r a p i d d a t a

accumulation, e.g., a scan from 40 to 400 atomic mass u n i t s (AMU) w i th t h r e e

d a t a r ead ings a t each 1/8 of an AMU i n on ly one second. The computer also m a k e s it p o s s i b l e to store l a r g e amounts of d a t a , r a p i d l y access it, and then

1

search l a r g e l i b r a r i e s o f known compounds to match t h e unknown spectra.

However, t h e GC-MS system has some problems i n unequivocal ly i d e n t i f y i n g

unknowns using t h e computer l i b r a r y search. One of t h e problems is due to

i n a c c u r a c i e s or l a r g e d i f f e r e n c e s i n instrument c h a r a c t e r i s t i c s t h a t cause

real d i f f e r e n c e s between spectra from known compounds. Most l i b r a r y s p e c t r a

1. General Chemistry Div i s ion Quar t e r ly Report, J u l y through September 1979, Lawrence Livermore Laboratory, Livermore, CA, UCID-15644-79-3 (1979), p. 29.

1

‘

are taken on magnetic i n s t rumen t s , which produce d i f f e r e n t cracking p a t t e r n s

than do t he quadrupole in s t rumen t s i n GC-MS systems. Instrument manufacturers

are at tempting to reduce t h i s problem by using computer sof tware t h a t a d j u s t s

t h e r e l a t i v e peak i n t e n s i t i e s from d i f f e r e n t instrument types to match a t h e o r e t i c a l “ s t anda rd instrument.’

A second problem invo lves t h e Probabili ty-Based Search (PBS) algori thm

used for sea rch ing l i b r a r i e s . Th i s a lgori thm, developed by McLafferty and

co-workers,2 can use e i t h e r condensed or f u l l l i b r a r y s p e c t r a f o r

searching. The condensed sea rch is most f r e q u e n t l y used, s i n c e it

s i g n i f i c a n t l y reduces the sea rch ing time. For example, to sea rch a l l

compounds between t h e molecular weights of 113 and 156, a condensed s e a r c h

takes 50 seconds whereas a f u l l s ea rch takes 660 seconds. The condensed

s p e c t r a i n t h e l i b r a r y c o n s i s t of 10 peaks chosen f o r both t h e uniqueness of a

p a r t i c u l a r mass and the i n t e n s i t y . Unfortunately, t h e condensed s p e c t r a of t h e l i b r a r y are compared to the f u l l spectra of t h e unknown sample. The

fo l lowing example i l lustrates t h e problems t h a t arise wi th t h i s approach and the need for an improved algori thm to i n c r e a s e t h e r e l i a b i l i t y for t h e

condensed search rou t ine .

A mixture of 10 pure normal a lkanes, C-6 through C-16, was i n j e c t e d i n t o

t h e GC-MS. The spectrum f o r each pure alkane was ob ta ined by manual s e l e c t i o n

of peak c e n t e r s and c o r r e c t e d f o r s o l v e n t or column bleed. For each spectrum,

t h e computer used t h e PBS algori thm to sea rch t h e l i b r a r y spectra to come up

wi th t h e b e s t matches (a maximum of 10 ) . Table 1 g i v e s an example of t h e

r e su l t s - - the computer matching f o r C-10, n-decane.

As can be seen, t h e r e s u l t s are discouraging: t h e t r u e i d e n t i t y of t h e

compound used is l isted as t h e e i g h t h and n i n t h cho ices , w h i l e t h e f i r s t t w o

choices are branched C-8 alkanes. Figure 1 shows t h e condensed l i b r a r y

s p e c t r a of t h e f i r s t cho ice (2,5-dimethylhexane) and t h e e i g h t h cho ice

(n-decane) v s t h e i n j e c t e d n-decane. By v i s u a l inspec,tion, it is obvious t h a t

t h e l i b r a r y spectrum of n-decane matches much more c l o s e l y than t h e l i b r a r y

spectrum of 2,s-dimethylhexane picked by t h e computer.

A b e t t e r , but somewhat more the-consuming, approach is to f i r s t f i n d t h e

10 b e s t fits using the condensed spectra, and then repeat t h e search using t h e

f u l l s p e c t r a of only t h e s e 10 compounds.

approach, a g a i n using n-decane as t h e unknown. As can be seen, t h i s approach

Table 2 shows an example of t h i s

2. F. W. McLafferty, R. H. Herlel and R. D. V i l l w o e c k , Org. Mass Spectry. 2,

2

690 (1974).

TABLE 1. Results of probability-based computer search of library spectra to match the spectrum of

n-decane, when condensed spectra are searched.

Confidence Compound Index

2,5 -D h e t hy 1 hexane .9796

3,3-Dimethylhexane .9780

2,2,3,3-Tetramethylpentane

3-Met hyl-2-Propylpentanol

n-Pentyl Bromide

3-Bromopentane 2-Bromopentane

n-Decane (source 1)

n-Decane (source 2)

.9775

.9751

.9726

.9706

.9703

.8791

.8708

gives only two library spectra that really match the full unknown spectra, and

both of them are n-decane. Another problem faced by GC-MS is differentiation between isomers. Figure

2 shows the mass spectra of 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene;

they are essentially identical. Since isomeric information can be critical,

especially in toxicological studies, data other than mass spectra are needed. A possible solution to this problem is to add the information of infrared

spectrometry (IR) . Infrared spectra are quite specific in separating and

'TABLE 2. Results of probability-based

computer search of library spectra to

match the spectrum of n-decane, when condensed spectra are searched to find

the 10 best fits and then the full spectra of those 10 are searched.

Con f i dence

Compound Index ~~

n-Decane (source 1) .8480 n-Decane (source 2 ) .5964

3

4 L 2 49

1 1 I I i

100

--17.11

40 II

TOTAL .8.82

n-decane (as injected)

9.41

140

V. TOTAL

2,5-dimethylhexane (condensed library spectrum)

140

n-deca n e (conden sed library spectrum)

140

FIG. 1. Comparison of the unknown spectrum (n-decane) with the GC-MS condensed

library spectra of the first choice of the library search (2,5-dimethylhexane)

and the eighth choice (n-decane).

4

60..

40..

20.. J.

0. 20 40 60 80 100

8.

48 60 80 100

.. 12Q 140 160

Mt””4k li - 3 140 160

FIG. 2. Example of the mass spectra of two isomers, showing the lack of

d iff er ent i a t i on.

5

i d e n t i f y i n g isomeric compounds.

1,2,4-trimethylbenzene and l r3 ,5- t r imethylbenzene; t h e d i f f e r e n c e s are

Figure 3 shows t h e l i b r a r y I R spectra of

obvious, e s p e c i a l l y a t 1600, 1500, 840, 800, and 690 wavenumbers.

On t h e other hand, I R spectrometry has g r e a t d i f f i c u l t y i n d i f f e r e n t i a t i n g

between long-chain hydrocarbons t h a t d i f f e r by on ly one carbon, whereas t h e

mass spectrometer can e a s i l y make t h i s d i s t i n c t i o n s i n c e each of t h e s e

hydrocarbons have molecular ions of u s e f u l i n t e n s i t y . To i l l u s t r a t e t h i s ,

Fig. 4 shows the gas-phase I R s p e c t r a of t h e C-15 and C-16 normal a lkanes.

The very s l i g h t d i f f e r e n c e i n i n t e n s i t y a t 2970 and 2860 wavenumbers would be

u s e f u l only under i d e a l cond i t ions ; although d i f f e r e n t , liquid-phase spectra

of these same compounds are no more d i f f e r e n t i a t e d than gas-phase spectra.

Thus, MS and I R are n a t u r a l l y complementary techniques; moreover, t h e

a v a i l a b i l i t y of FTIR opens t o t a l l y new p o s s i b i l i t i e s f o r combining t h e s e

instruments . With t h e a d d i t i o n of a cryogenic detector and a 2-ml-volume,

l i g h t - p i p e gas cell to t h e D i g i l a b FTIR instrument , w e can scan and record an

e n t i r e spectrum with 8 cm-’ i n 0.5 sec. The i n i t i a l experiments w i l l involve connecting t h e o u t p u t of t h e GC i n

t h e GC-MS to t h e FTIR instrument and then back to the M S , so t h a t peaks can be

d e t e c t e d by both methods.

sequence i n complex GC runs, which would occur i f s e p a r a t e GC-MS and GC-IR

runs were made. S ince t h e FTIR technique is 10 times less s e n s i t i v e than t h e

MS (10-ng v s 1-ng sample s i z e ) , l a rge r -capac i ty GC columns have to be used to

i n c r e a s e sample volume. W e have acquired both a Support Coated Open Tubu la r

(SCOT) column and a wide-bore (0.32 mm vs t h e normal 0.2 mm) Wall Coated Open

Tubular (WCOT) column, which w i l l i n c r e a s e sample volume by t w o to fou r times. The GC oven has been modified to t a k e gases i n and o u t through needle

Th i s e l i m i n a t e s t h e p o s s i b i l i t y of l o s i n g peak

va lves and heated l i n e s .

the FTIR instrument . If peak-spreading occurs i n t h e l i g h t pipe and t h e

series connection does no t work, p a r a l l e l o p e r a t i o n w i l l be t e s t e d using a s p l i t t e r a t t h e end of t h e GC column.

These l i n e s w i l l be connected to t h e l i g h t pipe i n

Primary accomplishments for t h i s i n i t i a l quarter were t h e design of

i n i t i a l experiments, o r d e r i n g of equipment and s u p p l i e s , i n s t a l l a t i o n and

t e s t i n g of t h e GC-IR attachment, and t r a i n i n g of personnel on t h e major

instruments .

6

60 - -

-

- 1,2,4,-trimethylbenzene

100 1 I 1

80 - 60 -

40

20

0- 4000 3500 3000 2500 2000 1800 1600 1400 1200 1000 800 600 400

-

1 - I -

- -

I, I/ 1,3,5 -trimethylbenzene I I I I 1

F I G . 3. Example of t he i n f r a r e d s p e c t r a of t w o isomers, showing t h e marked

d i f f e r e n t i a t i o n .

7

100

80

60

40

+ 8 80 - -

60 - -

40

20 -

-

Hexadecane -

0 - I I ' I I

20 8

E

C

$ 0 + .-

Pentadecane

FIG. 4. Example of the infrared spectra of adjacent members of a homologous

s e r i e s , showing the lack of d i f f erent ia t ion .

8 .

Improved I n l e t f o r Q u a n t i t a t i v e Mass Spectrometry

Responsible Personnel: R. W. Crawford, C. M. Wong, and K. B. Raut*

B r i e f Descr ipt ion: W e are doing experiments to test an appa ra tus f o r t h e

on-l ine cryogenic (-196OC) s e p a r a t i o n of g a s e s a t

t h e i n l e t of a mass spectrometer . T h i s technique w i l l

be e v e n t u a l l y a p p l i e d to t h e CEC Model 21-103C mass

spectrometer to improve t h e q u a n t i t a t i v e a n a l y s i s of

complex mixtures .

S t a tus : The p rev ious experiments t h a t showed promise f o r t h i s c ryogen ic

technique were done on a quadrupole mass spectrometer .3

were done on t h e t ime-o f - f l i gh t (TOF) mass spectrometer t h a t was used f o r

on-l ine a n a l y s i s i n t h e underground c o a l - g a s i f i c a t i o n f i e l d test (Hoe C r e e k

No . 3 ) . The t w o main advantages of using t h i s spectrometer were i ts

c o m p a t i b i l i t y w i th an a v a i l a b l e computer system (a portable LSI-11 system

designed f o r t h e UTI Corporat ion quadrupole mass spec t romete r ) and its proven a n a l y t i c a l performance. The i n l e t of t h i s instrument is a continuous-flow

type, which e l i m i n a t e s t h e changes i n p a r t i a l pressure wi th t i m e t h a t are c h a r a c t e r i s t i c of r e s e r v o i r i n l e t s . Th i s allowed u s to s i m p l i f y t h e

experiments.

Recent experiments

The technique used is as fol lows. Af t e r c a l i b r a t i o n wi th pure gases , a

gas mixture is analyzed and its spectrum is recorded i n t h e normal f a sh ion . l i q u i d - n i t r o g e n (-196OC) t r a p is then placed between the go ld l e a k and t h e

m a s s spectrometer. A second spectrum, which c o n s i s t s of gases t h a t are no t

condensed a t -196OC (H2, N2, 02, A r , Co, and C H 4 ) , is recorded.

computer t h e n takes t h e d i f f e r e n c e between t h e f i r s t and second spectra and

records it as t h e condens ib l e s (CO 2, C2H6, C3H8, C4Hlo) . is calculated s e p a r a t e l y .

and condensible f r a c t i o n s are then summed and normalized.

A

The

Each spectrum

The calculated p a r t i a l p r e s s u r e s of t h e noncondensible

Table 3 shows t h e results of f i v e replicate runs f o r t h e de t e rmina t ion of 0.99% A r , 27.77% C02, n i t rogen .

24.56% cot 41.00% HZ, 5.05% CH4, 0.31% C2H6, 0.12% C3H8, and 0.10% n-C4H10.

The analyzed g a s mixture contained 1.00% N 2'

* Summer I n s t i t u t e p r o f e s s o r , Savannah (Georgia) S t a t e College. 3. General Chemistry Div i s ion Q u a r t e r l y Report , A p r i l through June 1979,

Lawrence Livermore Laboratory, Livermore, CA, UCID-15644-79-2 (1979), p. 6.

9

TABLE 3. R e s u l t s of t he determinat ion of n i t rogen i n gas mixtures by mass

spectrometry using t h e cryogenic i n l e t system.

determined as mean of 12 runs using t h e CEC 21-103C mass spectrometer. (See

t e x t for o t h e r gas Cons t i t uen t s . )

Known va lue = 1.00% N2,

Normal technique Cryogenic t rap technique

N2 Run N2 Run

number found, % number found, %

1 0.35 1 0.66

2 0.69 2 0.87

3 0.75 3 0.90

4 0.86 4 1.00

0.97 5 0.50 5

Mean 0.63 Mean 0.88

Standard d e v i a t i o n 0.20 Standard d e v i a t i o n 0.12

B i a s -0.37 B i a s -0.12

-

r

This mixture was used because it is typical of t h e complex samples received

from f o s s i l - f u e l programs.

The results of t h e s e ana lyses are encouraging. The p r e c i s i o n of t h e

n i t r o g e n de te rmina t ion using t h e new technique is almost t w i c e as good as t h a t

of the normal a n a l y s i s , and t h e accuracy is a f a c t o r of t h r e e b e t t e r . R e s u l t s

f o r the o the r c o n s t i t u e n t s are not shown, s i n c e they are q u i t e similar by both

methods. Nitrogen is more a c c u r a t e l y determined by t h i s method because it is

p r e s e n t i n l o w concen t r a t ions , and because it is subject to i n t e r f e r e n c e by

t h e C02 and higher hydrocarbons.

f u r t h e r .

a n a l y s i s can be made on a peak-by-peak b a s i s . I n t h i s m o d e , each p a r t i c u l a r

mass would be read f i r s t f o r t h e e n t i r e mixture , and then f o r noncondensibles

only. Each peak i n t h e spectrum would be read i n sequence; t h i s would-allow

t h e method to be adapted to r e s e r v o i r - i n l e t systems.

We w i l l perform more experiments w i th v a r i o u s mixtures to prove t h e method

A s p e c i a l s h u t t l e - v a l v e system w i l l t hen be t e s t e d so t h a t t h e

1 0

Analyses of Fluorocarbon FC-86 wi th t h e

G a s Chromatograph-Mass Spectrometer

Responsible Personnel: J. C. Newton and R. W. Crawford

B r i e f Descr ipt ion: The components of a sample of a f luorocarbon mixture

produced commercially were i d e n t i f i e d by gas

chromatography-mass spectrometry.

S t a tus : G a s chromatography-mass spectrometry (GC-MS) is proving to be u s e f u l

i n numerous s tud ies i n the General Chemistry Division.'

of t h e f luorocarbon FC-86, which was stated to be p r i n c i p a l l y perf luorohexane,

was submit ted f o r a n a l y s i s . I t was of particular i n t e r e s t to know i f t h e

sample contained any r e a c t i v e i m p u r i t i e s . A Porasil-packed chromatographic

column was used to s e p a r a t e t h e sample and t h e chromatographic e f f l u e n t was

analyzed by the mass spectrometer . Because t h e l i q u i d boils a t 56-58OC, it

was necessary to cool t h e s y r i n g e with d ry ice be fo re drawing t h e l i q u i d

sample i n t o t h e sy r inge . G o o d s e p a r a t i o n of t h e i m p u r i t i e s was obtained. The

column was temperature-programmed from 150 to 190°C a t a rate of

3O~/mi nu te .

Recent ly a sample

F igu re 5 s h o w s t h e total number of ions (recorded by t h e mass spectrometer

as t h e peaks were e l u t e d from t h e gas chromatograph) p l o t t e d a g a i n s t time.

The i d e n t i f i c a t i o n of t he peaks is shown i n Table 4. Peak 7 was a t t e n u a t e d by

t u r n i n g t h e high v o l t a g e on t h e m u l t i p l i e r down while t h e peak was o f f scale. Thus pe r f luo rohep tane appears to be p r e s e n t i n a l a r g e r concen t r a t ion than

perfluorohexane. The l a s t two peaks c o u l d not be i d e n t i f i e d because of t h e

absence of molecular ion peaks. However, t hey are probably higher homologs of

t h e pe r f luo roca rbons e l u t e d a t earlier times. *

The component i n peak 5 is of p a r t i c u l a r i n t e r e s t because it c o n t a i n s mass

peaks a t 135, 147, and 197. Th i s can be exp la ined by inc lud ing an oxygen atom

i n the fragments to i d e n t i f y t h e p e a k s as C F 0 , C F O', and C F O',

r e s p e c t i v e l y . To e s t a b l i s h t h e r e a c t i v i t y of t h i s compound, i n f r a r e d ana lyses were performed (by R. Sanborn), and it was found t h a t t h e component was not an

aldehyde, ketone, or ca rboxy l i c acid. Peak 5 is thought to be an e t h e r , a

common impur i ty i n f luo roa lkanes .

+ 2 5 3 5 4 7

11

Mass 135

Mass 69

Total ions

I Time ( m i d

FIG. 5. GC-MS p l o t of the total ions, mass 69 , and mass 135 for fluorocarbon

FC-86.

12

Table 4. Compounds i d e n t i f i e d i n t h e GC-MS spectrum of F ig . 5.

R e t en t i on Peak time Compound Formula

6.7

7.4

8.4

9.9

10.7

12.0

13.4

15.2

17.5

Per f luoropentane

Dia lky lpe r f luo ro

e t h e r

Perf luorocyclohexane

Per f luorohexane

D i a1 kylper f l u o r o

e t her

Per f luorocycloheptane

Per f luoroheptane -

C F 5 1 2 -

‘SF12

‘gF14

‘gF14’

C7F14

C7F16

-

There is some suppor t ing evidence t h a t peak 5 is an e t h e r . Because peak 5

appears j u s t after t h e perf luorohexane peak, it l i k e l y has a similar b o i l i n g

p o i n t .

p e r f l u o r i n a t e d d ip ropy l ether, C F OC F However, from t h e d a t a i n

Fig. 5 , the compound appears to be e t h y l b u t y l p e r f l u o r o e t h e r or methyl

p e n t y l p e r f l u o r o e t h e r .

a v a i l a b l e but can be expected, by comparison to t h e homologous hydrocarbons,

to be similar to t h a t of C3F70C3F7.

mixture.

Perf luorohexane boils a t 56OC, which sugges t s t h a t peak 5 is due to

3 7 3 7 ’

The b o i l i n g p o i n t s of t h e s e compounds are not

Fu r the r work w i l l include ana lyz ing t h e a v a i l a b l e pure components of t h i s

13

Far-Infrared Laser Development

Responsible Personnel: W. A. B o o k l e s s , * C. G. Stevens, L. W. Hrubesh, and t D. C. Johnson

B r i e f Descr ipt ion: The development of t h e f a r - i n f r a r e d (F IR) laser progressed i n t h r e e areas. F i r s t , it was found t h a t

s h o r t pulses (-5 ns) are necessary f o r optimal energy

ou tpu t , so we ob ta ined a pulsed nitrogen-pumped dye

laser f o r t h e system. Second, v a r i o u s o the r methods

were used to i n c r e a s e t h e ou tpu t power of t h e FIR

laser by a f a c t o r of 50. Third, w e designed and

t e s t e d a wavelength-measurement device, using

microwaves to simulate t h e F I R laser output .

S t a tus : .Work proceeded s a t i s f a c t o r i l y on t h e development of t h e tunab le f ar- inf r a red (FIR) laser, ** i n t h r e e s p e c i f i c areas:

1) I n experiments w i t h va r ious pumped-laser sources w e found t h a t a short p u l s e is e s s e n t i a l to t h e super-f luorescent process being used to gene ra t e F I R

r a d i a t i o n .

is necessary to achieve e f f i c i e n t power o u t p u t . To f a c i l i t a t e t h i s we obtained

a pulsed nitrogen-pumped dye laser from t h e LIS Group of Y-Division on long-

term loan. Th i s w i l l i n c r e a s e our beam t i m e and t h u s speed progress .

Experiments i n d i c a t e t h a t a p u l s e l e n g t h i n t h e nanosecond regime

2) Through va r ious a l t e r a t i o n s i n working p r e s s u r e , temperature, and

o p t i c a l c o n f i g u r a t i o n s , w e i nc reased t h e power o u t p u t of t h e laser by a factor

of 50. Th i s is s i g n i f i c a n t , because w e can now do spectroscopy on t h e l a s i n g

l e v e l s by observing e f f e c t s on t h e FIR power ou tpu t w i th s h o r t (1-sec) t i m e

cons t an t s . W e have done scans of t h e W pump beam through t h e 13p abso rp t ion

state of the potassium and observed t h e FIR o u t p u t shown i n Fig. 6. F igu re 6a

shows t h i s s can observed wi th a Golay d e t e c t o r . F igu res 6b and c show t h e

same scan with a liquid-helium-cooled, gallium-doped germanium bolometer. By

using the’GaGe bolometer we r e a l i z e d an improvement i n signal-to-noise ratio by a f a c t o r of 8 i n a d d i t i o n to t h e s i g n a l g a i n of 50.

* Associated Western U n i v e r s i t i e s research fellow, Unive r s i ty of Wyoming.

**See R e f . 3, p. 9. Mechanical Engineering Dept., LLL.

14

f , 292.75 I I

I 292.75 292.75

I Wavelength of UV pump laser ( n m )

FIG. 6 . FIR emission from the 13p s t a t e of potassium, fol lowing e x c i t a t i o n

from t h e 4 s s ta te by a pulsed frequency-doubled nitrogen-pumped dye laser

(wavelength = 292;75 nm). The traces s h o w t h e FIR o u t p u t i n t e n s i t y vs t h e

wavelength of t h e pumped laser as t h e pumped laser is scanned through t h e

4s-13p absorpt ion.

laser by a lock-in a m p l i f i e r with a 1-second t h e cons tan t . a) Detected with

a Golay cell ; s ignal- to-noise ra t io (S/N) = 5.6. b) Detected wi th a

gallium-doped germanium bolometer ( 4 K ) ; S/N = 10 , b i a s = 1.3 V. c) Detected

w i t h a gallium-doped germanium bolometer ( 4 K ) ; S/N = 4 0 , b ias = 1.45 V.

The d e t e c t o r ou tpu t w a s synchronized wi th t h e pulsed W I

15

3 ) W e designed a modified Fabry-Perot interferometer to measure the

wavelength of the FIR and te s ted the design with microwaves that simulate

the FIR. I n i t i a l tests indicate that the reso lut ion is s u f f i c i e n t to

determine which of the poss ib le l a s i n g l e v e l s are ac tua l ly involved i n the

stimulated emission.

16

Photoelectrochemistry

Responsible Personnel: J. H. Richardson, S. B. Deutscher, S. P. Perone,* and

J. E. Harrar

B r i e f Descr ipt ion: 2

C o u l o s t a t i c l a s e r - f l a s h i r r a d i a t i o n of n-type T i 0

semiconductor e l e c t r o d e s permitted measurements of

t r a n s i e n t p h o t o p o t e n t i a l excur s ions wi th 10-ns time

resolution. p h o t o p o t e n t i a l on t h e i n i t i a l electrode p o t e n t i a l , t h e

laser i n t e n s i t y , and t h e n a t u r e and c o n c e n t r a t i o n of

e l e c t r o l y t e was cha rac t e r i zed . The i n i t i a l

p h o t o p o t e n t i a l appears to be r e l a t e d to t h e t r a n s i e n t

expansion of t h e space-charge l a y e r t h a t is due to

rapid photo-induced charge i n j e c t i o n ; t h i s is

analogous to t h e double-layer expansion seen i n

classical e l ec t rochemica l s t u d i e s . The subsequent

p h o t o p o t e n t i a l decay appears to fo l low a time

dependence similar to t h a t p r e d i c t e d for double-layer

r e l a x a t i o n .

The dependence of " t h i s t r a n s i e n t

F

S t a t u s : A manuscript d e s c r i b i n g t h e results and sugges t ing o u r i n t e r p r e t a t i o n

based on space-charge r e l a x a t i o n is n e a r l y complete. Experiments were done

w i t h fou r d i f f e r e n t n-type T i 0 semiconductor e l e c t r o d e s . The e l e c t r o d e s

were c h a r a c t e r i z e d byy t h e i r Mott-Schottky p l o t s and by c y c l i c voltammetry; t h e

r e s i s t a n c e and capac i t ance of t h e electrodes v a r i e d by an order of magnitude,

and t h e doping d e n s i t y by two o r d e r s of magnitude.

2

The e l ec t rochemica l cell w a s modified from t h a t used previously.+ A

c y l i n d r i c a l platinum-gauze e l e c t r o d e was used as t h e f o u r t h e l e c t r o d e ( t h e

quas i - r e fe rence electrode) , for monitoring t h e r a p i d p h o t o p o t e n t i a l t r a n s i e n t s .

A hemi-cyl indrical platinum-gauze electrode of t h e same area was used as t h e

counter-electrode. These electrodes were o r i e n t e d c o n c e n t r i c a l l y to t h e

semiconductor e l e c t r o d e . The laser system, t iming c i r c u i t r y , and e l e c t r o n i c

measurement apparatus were ident ical to those described previously. .t.

* Department of Chemistry, Purdue Un ive r s i ty , La faye t t e , Indiana. ' See Ref. 1, p. 23.

17

The e l e c t r o l y t e used was u s u a l l y aqueous 1M, KN03. Similar r e s u l t s were

obtained w i t h 1M, KC1 or 0.5M K 2 S 0 4 .

0.01M KN03, i n d i c a t i n g that t h e decay of t h e p h o t o p o t e n t i a l t r a n s i e n t was not due to double-layer r e l a x a t i o n . However, t h e short- t ime response

(risetime) was cons ide rab ly slowed i n t h i s s o l u t i o n , i n d i c a t i n g t h a t t h e

higher s o l u t i o n r e s i s t a n c e inc reased t h e measurement t ime cons t an t .

The long-time response was similar i n

The response of the va r ious electrodes to i r r a d i a t i o n were c h a r a c t e r i z e d

wi th both cw i r r a d i a t i o n (by measuring t h e photocurrent) and pulsed

i r r a d i a t i o n (by measuring t h e photocurrent and p h o t o p o t e n t i a l ) . It is

s i g n i f i c a n t t h a t much f a s t e r t r a n s i e n t s could be observed i n t h e

p h o t o p o t e n t i a l ( c o u l o s t a t i c ) m o d e than i n t h e photocurrent mode (10 n s vs

100 ps)? even under c i rcumstances where no n e t charge t r a n s f e r t o o k place.

Table 5 summarizes t h e results obtained for t h e fou r n-type T i 0 semicondctor

electrodes. 2

The m o s t i n t e r e s t i n g obse rva t ion is t h e decay of t h e i n i t i a l p h o t o p o t e n t i a l

to a h n a l va lue ( r ep resen ted by %inal/AE

possible explanat ions. The f i r s t is t h a t the decay is due to a dark

back-reaction of photo-oxidation products produced by t h e f lash . Such a

mechanism would be more s i g n i f i c a n t as t h e e l e c t r o d e p o t e n t i a l approached t h e

f la t -band p o t e n t i a l , as indeed was observed (Table 5 ) . However, t h e rate is

e l e c t r o l y t e independent, a l though the possible role of t h e s o l v e n t needs to be

clarified. The second exp lana t ion is e l ec t ron -ho le recombination. This

process g e n e r a l l y occurs much f a s t e r a t the doping d e n s i t i e s used than

observed here, a l though t h e r e are no previous measurements of t h i s rate a t an

e l e c t r o d e / e l e c t r o l y t e i n t e r f a c e (band-bending would tend to decrease t h e rate

of recombination by i n c r e a s i n g t h e spat ia l s e p a r a t i o n of e l e c t r o n s and holes).

i n Table 5 ) . There are t h r e e Max

The t h i r d exp lana t ion is t h a t t h e r e is a t r a n s i e n t nonequilibrium

expansion of t h e space-charge region i n t h e semiconductor, followed by a r e l a x a t i o n back to its equ i l ib r ium dimensions, w i th an associated overshoot

and decay of the pho topo ten t i a l . Such a r e l a x a t i o n effect has been observed

wi th coulostatic electrical charge i n j e c t i o n a t a mercury/dilute e l e c t r o l y t e

i n t e r f a ~ e . ~

an i n i t i a l over-expansion of t h e Helmholtz l a y e r ( i n t e r f a c i a l double l a y e r )

followed by a r e l a x a t i o n back to an equ i l ib r ium th i ckness , w i th corresponding

changes i n the measured double-layer potent ia l - -very similar i n n a t u r e and

I n that case the t r a n s i e n t response was descr ibed i n terms of

4. S. W. Feldberg, J. Phys. Chem. 74, 87 (1970). - 18

TABLE 5.

resul ts ( i n 1% K N 0 3 ) .

S m X Y of n-tYJ?e Tio2 semiconductor electrode c h a r a c t e r i s t i c s and

E lec t rode

A B C D

0.11 0.14 0.20 0.21 2 Area (cm ) Resistance (52) 330 29 38 86

Capacitance a t 1.0 V v s SCE (WF) 0.14 2.2 1.8 1.8

Doping d e n s i t y ( ~ m - ~ ) 1.6 x 10l8 3.0 x 1 0 2o 1.4 x 10 2o 1.5 x 10 20

F l a t band poten t ia l (V vs SCE) -0.4 -0.75 -0.53 -0.80

Threshold poten t ia l ( V v s SCE)

c w photocurren t -1.1 -1.1 -0.88 -0.93

pulsed photocurren t -0.55 - -0.50 -0.50

pu 1 sed pho topoten t i a1 -1.3 -1.3 -0.90 -1.1

R i s e t h e (ns)

near f l a t b a n d 12 10 12 12

1.5 V vs SCE 12 10 15 12

Time to f i n a l va lue ( m s )

near f l a t b a n d

1.5 V v s SCE

1 0.05 0.18 0.15

20 2.2 1 1

near f l a t b a n d 0.10 0.18 0.13 0.20

1 .5 V v s SCE 0.15 0.76 0.56 0.41

t h e dependence to t h a t observed here. T h i s exp lana t ion was f u r t h e r substantiated by comparing t h e observed time dependence to t h e t h e o r e t i c a l l y

predicted time dependence. Holes and electrons can be s u b s t i t u t e d f o r c a t i o n s

and an ions i n t h i s theory , w i t h corresponding changes i n mobilities and

concen t r a t ions . The semiconductor 's d e p l e t i o n l a y e r replaces t h e s o l u t i o n ' s

Helmholtz double-layer t h i ckness , and t h e f l a t band p o t e n t i a l replaces t h e

p o t e n t i a l o f ze ro charge. The modified theo ry predicts a t i m e dependence of t h e pho topo ten t i a l , and as shown i n Fig. 7 , t h i s was observed

near the f l a t band p o t e n t i a l and a t long times.

-2/3

These s t u d i e s provide a foundat ion f o r f u r t h e r i n v e s t i g a t i o n s of t h e

t r a n s i e n t behavior of o the r semiconductor pho toe lec t rodes and o t h e r

p h o t o e l e c t r o l y s i s processes. I t should now be possible to s tudy t h e dynamics

o f redox s t a b i l i z e d pho toe lec t rodes as w e l l as dye-sens i t ized p h o t o e l e c t r o l y s i s

on a previously inaccessible time scale.

-- ___-_____- -----.----

19

80

70

60

50

40

30

20

10

500 100 50 20 10 4 1 1 I 1 I I

0 0

/ /

/ / :

/ *

0.1 0.2 0.3

Time -2t3

0.4 0.5 0.6

FIG. 7 . Photopotential vs t i m e -2’3 for n-type T i 0 2 e lectrode

(electrode D, -0.5 V vs SCE, 1.0& Io3, laser paver = 28 kw).

20

Contamination S t u d i e s f o r t h e Weapons Development Program

Responsible Personnel: S. B. Deutscher, E. T. Mones,* and R. J. Morgan*

Br i e f Desc r ip t ion : The long-term d u r a b i l i t y of Kevlar 49 f i b e r s ( i n t h e /------ -- --.--__.

form of epoxy s t r a n d s and m u l t i l a y e r composites) under

stress is c u r r e n t l y under study.5 The behavior of

t h e major contaminant, Na2SO4, a t t h e i n t e r f a c e of

t h e f i b e r and t h e epoxy m a t r i x is a major concern.

Analyses of the f i b e r s and water used to wash t h e

f i b e r s showed t h a t N a SO is p r e s e n t on t h e 2 4

s u r f a c e of as w e l l as inco rpora t ed i n t h e f i b e r , and

t h a t t h e occluded Na2SO4 can d i f f u s e o u t of t h e

f i b e r .

S t a t u s : + followed by a NaOH wash.

i o n s are a f f e c t i n g t h e f i b e r ' s f a i l u r e p rocesses and i t s d u r a b i l i t y i n

long-term weapons a p p l i c a t i o n s . Three samples of d i f f e r e n t f i b e r ba t ches , t w o

c o n s i s t i n g of f o u r f i l amen t s and t h e o the r of one f i l amen t , and t h e water used

to wash them were analyzed for t h e i r N a SO con ten t .

The p rocess ing of Kevlar 49 by DuPont i nvo lves HzS04 t r ea tmen t

There is concern t h a t res idua l SO 2- and N a 4

2 4 Samples varying from 1 to 3 g were placed i n HN03-washed 400-ml beakers,

covered wi th deionized H20 , and allowed to sit with occas iona l s t i r r i n g f o r

t h r e e p e r i o d s of .time: 6 h, 11 days, and 15 days. A t t h e end of t h e a l lot ted t i m e t h e f ibers were sepa ra t ed by f i l t r a t i o n and washed. The f i l t r a t e w a s

evaporated to a specific volume and analyzed. The f i b e r samples were allowed

to a i r - d r y f o r s e v e r a l days, weighed, and then combusted i n a platinum-lined

Pa r r bomb under oxygen. The combustion p roduc t s were absorbed i n a KOH

s o l u t i o n , which was then d i l u t e d to volume. Sodium ana lyses were performed

using atomic abso rp t ion spectrophotometry. Sulfate was determined by a p o t e n t i o m e t r i c t i t r a t i o n wi th a lead i o n - s e l e c t i v e electrode and a t i t r a n t of

lead pe rch lo ra t e .6 Ash weights were ob ta ined by p l a c i n g t h e f i b e r i n a

* Organic Materials Divis ion. 5. R. J. Morgan, E. T. Mones, W. J. Steele, and S. B. Deutscher, The

D u r a b i l i t y of Kevlar 49 F ibers , Lawrence Livermore Laboratory, Livermore, CA, UCRL-83599 (1979).

6. W. S e l i g , Mikrochim. Acta(Wein) 1970, 168.

2 1

plat inum c r u c i b l e and hea t ing f o r 8 h a t 700°C i n an oxygen atmosphere.

a d d i t i o n , a multi-element a n a l y s i s of t h e s o l u t i o n s was done by ICP

spectrometry.

I n

The results of t h e ICP a n a l y s i s are given i n Table 6. The r e s u l t s of t h e

w e t chemical ana lyses of t h e t h r e e samples of Kevlar ( t r e a t e d and un t r ea t ed )

and of the water used to wash t h e f i b e r s are shown i n Table 7.

The r e s u l t s i n d i c a t e that N a SO is indeed p r e s e n t both on t h e s u r f a c e 2 4 o f the f i b e r and between t h e f i b r i l s , and t h a t t h e occluded Na2S04 can

d i f f u s e o u t of the f i b e r . Fu r the r spectroscopic work is being done (by x-ray

d i f f r a c t i o n , scanning e l e c t r o n microscopy, and Fourier- t ransform i n f r a r e d

spec t roscopy) , to determine whether t h e impurities can d i f f u s e through t h e

epoxy, a f f e c t i n g t h e i n t e g r i t y of t h e composite.

1

22

TABLE 6.

by ICP spec t romet ry ( concen t r a t ion i n mg/kg).

Composition o f Kevlar 49 and wash waters as determined .-

Samplea

Wash waters from f i b e r s

F i b e r s washed a t 6 h washed a t 15 days

A C A B C b Element

N a 1563 1251 283 299 349

S i 24 19 53 10 39

P 17 4 ndc 44 nd nd

B 0.5 1 4 23 36

K 10 6 65 6 nd

Ca 2 3 0.2 2 14

Fe 2 1 1 0.3 0.3

A 1 1 1 nd nd nd

Mg 1 1 0.1 0.5 2

L i 0.5 0.4 nd nd nd

Zn 0.1 0.02 0.1 1 2

c u 0.2 0.04 0.2 0 . 1 0.1

T i 0.05 nd nd nd nd

Mn 0.006 nt3 nd nd 0 . 1

aSamples A and B were 4-fi lament f i b e r s ; sample C was a 1-f i lament

b N o t de t ec t ed i n any sample:

f i b e r .

As <0.6 Pb <0.2 Cd (0.01 Se (0.3 co <0.02 Sr C0.026 M o (0.01 U C0.64 N i (0.01 V <0.03

Z r (0.01

cNot d e t e c t e d .

23

TABU?, 7. Analysis of Kevlar-49 fibers and wash waters (concentrations in mg/kg) .

Wash waters from f i b e r s washed at: Untreated fibers F i b e r s washed a t 6 h 6 h 11 days 15 days

+ + 2- N a SO:- N a SO4 + 2- Ash N a SO4 + 2-

s04 Ash N a + 2- =4 N a a Sample

A 3850 59 30 12,270 3000 5240 10,500 140 590 270 410 270 450

B 38 10 6090 12,160 3000 5480 10,900 140 240 220 390 300 -

C 2770 59 30 9310 2300 3190 7210 280 330 270 380 300 - a Samples A and B were 4-f i lament f i b e r s ; sample C was a 1 - f i l amen t f i b e r .

h) P

B r i e f Descr ipt ion: Quaternary ammonium h a l i d e s were eva lua ted f o r t h e

po ten t iome t r i c t i t r a t i o n of small amounts of l a r g e

ino rgan ic and o rgan ic anions. E m f ' s were monitored

wi th liquid-membrane i o n - s e l e c t i v e indicator electrodes ( I S E ' s ) and a double-junction r e f e r e n c e

electrode. The same t i t r a n t s and electrode systems

were also used f o r t he de t e rmina t ion of i o n i c

s u r f a c t a n t s and soaps. I n a d d i t i o n , va r ious anions

were determined using solid-state ISE's as endpoint

s enso r s .

S t a tus : W e p rev ious ly reported s e v e r a l new t i t r a n t s f o r t h e p r e c i p i t a t i o n

t i t r a t i o n of p e r c h l o r a t e and f l ~ o r o b o r a t e . ~ ' ~

hexadecylpyridinium c h l o r i d e (CPC) , hexadecyltrimethylaonium c h l o r i d e (CEZAC), and benzy ld ime thy l t e t r adecy laon ium c h l o r i d e (BDTAC). CETAC and CPC

y i e l d e d t h e h i g h e s t p r e c i s i o n and l a r g e s t p o t e n t i o m e t r i c breaks. CPC has been

used i n f u r t h e r work w i th a l a r g e number of i no rgan ic and o r g a n i c anions.

Emf's were monitored with a fluoroborate ISE and a double-junction r e f e r e n c e

electrode. The p e r c h l o r a t e , n i t r a t e , and calcium ISE's also respond to t h e

va r ious anions and can also be used f o r emf monitoring.

The t i t r a n t s were

Sharp endpoint breaks were ob ta ined for permanganate, hexa f luo roa r sena te ,

hexafluorophosphate, p e r s u l f a t e , hexach lo rop la t ina t e , t e t r a c h l o r o a u r a t e ,

tetrachlorothallate(III), and o t h e r i n o r g a n i c anions. T i t ra tab le o rgan ic

anions are n i t ro fo rm, phenylborates , benzenesulfonates , 2 , 4 , 6 - t r i n i t r o -

compounds, and some su l fonph tha le ins . Because t h e liquid-membrane electrodes

f u n c t i o n on ly i n an aqueous medium, t h e method is l i m i t e d to o rgan ic anions.

7 . W. S e l i g , A New T i t r a n t f o r Pe rch lo ra t e : Cetyltrimethylammonium Bromide, Lawrence Livermore Laboratory, Livermore, CA, UCRL-82719 (1979).

8 . W. S e l i g , New T i t r a n t s for P e r c h l o r a t e and Fluoroborate, Lawrence Livermore Laboratory, Livermore, CA, UCRL-83153 (1979).

25

The details of t h i s work are p resen ted i n t w o reports t h a t have been 9,lO accepted for p u b l i c a t i o n i n Mikrochim. Acta.

The same t i t r a n t s and I S E ' s were also used to determine v a r i o u s a n i o n i c

s u r f a c t a n t s and soaps. This o b v i a t e s t h e need f o r p repa r ing t h e s p e c i a l

liquid-membrane or o the r e l e c t r o d e s u s e d h e r e t o f o r e i n t h e p o t e n t i o m e t r i c

t i t r a t i o n of s u r f a c t a n t s and soaps. W e recommend e l ec t rophores i s -g rade sodium

dodecylsulf ate f o r the s t a n d a r d i z a t i o n of t h e qua te rna ry ammonium h a l i d e

t i t r a n t s . The r e v e r s e t i t r a t i o n of c a t i o n i c s u r f a c t a n t s w i th s t anda rd sodium

dodecy l su l f a t e is s i m i l a r l y f e a s i b l e . Detai ls are p resen ted i n a report t h a t

has been submitted f o r p u b l i c a t i o n i n Zeitschrif t fur Analyt ische Chemie.11

p r e v i o u s l y i n v e s t i g a t e d ino rgan ic and o r g a n i c anions. '"O

l i m i t a t i o n of o p e r a t i n g i n a s t r i c t l y aqueous medium. The l a r g e s t endpoint

breaks were ob ta ined w i t h t h e iod ide and cyanide e l e c t r o d e s . I n most cases t h e t i t r a t i o n curves had shapes similar to those ob ta ined i n t h e nonaqueous

t i t r a t i o n of weak o rgan ic using t w o platinum electrodes p o l a r i z e d by a cons t an t c u r r e n t . They have t h e shape of an i n v e r t e d V, w i th a more or

W e have found t h a t s e v e r a l s o l i d - s t a t e I S E ' s also respond to many of t h e

Th i s o b v i a t e s t h e

less sharp peak after a steep rise i n p o t e n t i a l , followed by a d e c l i n e i n

e m f . I t is therefore p o s s i b l e to c a l c u l a t e t he endpoints by e i t h e r of t w o

methods: 1) the usual c a l c u l a t i o n of t h e maximum change i n emf vs t i t r a n t

increment, or 2) t h e p o i n t of maximum emf as w a s done by Shain and

Svoboda . 12

Some ino rgan ic anions t h u s t i t r a t ab le are pe r rhena te , p e r s u l f a t e ,

f e r r i c y a n i d e , hexafluorophosphate, and hexach lo rop la t ina t e . Examples of

t i t r a b l e o r g a n i c anions are ni t roform, t e t r apheny lbora t e , cyanotriphenyl-

borate, p i c r a t e , long-chain s u l f a t e s and s u l f o n a t e s , and some soaps. The

r e v e r s e t i t r a t i o n of qua te rna ry ammonium halides vs sodium dodecy l su l f a t e is

9. W. S e l i g , A Po ten t iome t r i c Study of Some Anions with Cetyltrimethylammonium Bromide. I. Ino rgan ic Anions, Lawrence Livermore Laboratory, Livermore,

10. W. S e l i g , A Po ten t iome t r i c Study of Some Anions w i t h Quaternary Ammonium Halides. 11. Orqanic Anions. Lawrence Livermore Laboratory, Livermore, CA, UCRL-83344 (1979).

Ion-Select ive E lec t rodes , Lawrence Livermore Laboratory, Livermore, :A,

CA, UCRL-83037 (1979).

11. W. S e l i g , The Po ten t iome t r i c T i t r a t i o n of S u r f a c t a n t s and Soaps Usin

UCRL-83495 (1979). 12. I. Shain and G. R. SvobOda, Anal. Chem. 31, 1857 (1959). 13. W. S e l i g , Microchem. J. - 24, 73 (1979).

26

also feasible. I n addition, some t i t r a t ions can be carried out i n a par t ia l ly nonaqueous medium.

Details are given i n a report that has been accepted for publication i n __c_____----- 14 7-- Microchemical Journal.

' 14. W. Selig, Microtitration of Various Anions w i t h Quaternary Ammonium Halides Using Solid-state Electrodes, Lawrence Livermore Laboratory, Livermore, CA, UCRL-83613 (1979).

27

I

ANALYTICAL RESEARCH AND DEVELOPMENT FOR THE ENERGY PROGRAMS

Automated, Po r t ab le , On-Line Mass Spectrometer f o r t h e Oil-Shale Program 'Y

,-

Responsible Personnel: R. G. Bedford and F. D a n i e l l i *

Br i e f Descr i p t i o n : Cont ro l of a commercial quadrupole spectrometer used

to analyze gases from o i l - s h a l e r e t o r t i n g

experiments l5 '16 was converted from a D-112

(PDP-8-type) computer to a DEC LSI-11 system. The

LSI-11 t h a t c o n t r o l s t h e mass spectrometer w i l l be

p a r t of a network t h a t i nc ludes a Tektronix model 4051

g r a p h i c s system to be shared wi th another LSI-11 used

f o r d a t a acquisit ion from gas chromatographs.

Status: The D-112 computer t h a t has been used to c o n t r o l t h e oil-shale

quadrupole mass spectrometer and high-temperature drop calorimeter is being

r e t i r e d from s e r v i c e and has been replaced wi th LSI-11 microprocessor

systems. The system t h a t controls t h e mass spectrometer inc ludes t h e

fol lowing hardware: Teletype model 43 t e rmina l , Data Systems DSD 440 dual double-density f loppy

d i s k , Western Dynex DD 6222 10-Mbyte d i s k w i th one f i x e d and one removable

c a r t r i d g e (top load.ing), GPIB i n t e r f a c e f o r Tektronix 4051 system, ADAC 12-bi t

A/D converter da t a -acqu i s i t i on board, 16 -b i t D/A conve r t e r (DRV-11 p a r a l l e l

i n t e r f a c e ) , and a Doric 2301 data logger (DLV-11 ser ia l i n t e r f a c e ) . The

12-bi t A/D conve r t e r w i l l be replaced later by a 14-bi t A/D conve r t e r .

LSI-11 microprocessor w i th 32K words of MOS memory,

New sof tware was provided to o p e r a t e t h e system. Programs were adapted

from the t ime-of-f l ight mass spectrometer used for t h e H o e C r e e k No. 3

underground coal-gasif i c a t i o n f i e l d experiment l as t summer .' are used: mass scale c a l i b r a t i o n , background measurement, spectral

c a l i b r a t i o n of pure gas s t anda rds , and d a t a a c q u i s i t i o n / d a t a reduct ion.

Four r o u t i n e s

I * E l e c t r o n i c s Engineering Department, LLL.

15. General Chemistry Divis ion Quar t e r ly R e p o r t , January through March 1977, See Ref. 1, p. 46.

Lawrence Livermore Laboratory, Livermore, CA, UCID-15644-77-1 (1977), p. 46. 16. General Chemistry Div i s ion Q u a r t e r l y R e p o r t , A p r i l through June, 1977, Lawrence

Livermore Laboratory, Livermore, CA, UCID-15644-77-2 (1977), p. 39.

28

R e s u l t s from the f i r s t three r o u t i n e s are saved i n d i s k f i l e s on t h e system

device and read back by t h e data a c q u i s i t i o n / r e d u c t i o n program.

The Doric data logger is programmed by t h e o p e r a t o r t o scan t h e

thermocouples or o the r vo l t age sources a t t h e d e s i r e d rate (maximum 1 scan pe r

minu te ) . Mass spectrometer data a c q u i s i t i o n is t r i g g e r e d by t h e Doric scans.

T h e d a t a a c q u i s i t i o n r o u t i n e records t h e Doric d a t a and t h e mass spectrum i n a

d i s k f i l e and then determines gas composition i n real t i m e using a s t epwise

l i n e a r r eg res s ion . The c a l c u l a t e d spectrum is w r i t t e n i n t h e f i l e w i th t h e

experimental d a t a and t h e composition i n a s e p a r a t e f i l e . Data f o r each scan

is saved i n a s e p a r a t e f i l e i n A S C I I code, and i d e n t i f i e d by scan number f o r

convenient access by t h e 4051. Doric d a t a and compositions are typed on t h e

console as they are ob ta ined i f des i r ed .

The program can scan up to 60 masses and inc lude 20 compounds i n t h e

r eg res s ion . The time required f o r a complete scan and computation f o r a

typical spectrum of 22 masses wi th 6 compounds i n t h e r e g r e s s i o n is less than

10 seconds. The program occupies a b o u t 18K words i n memory and is c u r r e n t l y being used wi th the RT-11 s ing le - job monitor because i t is too l a r g e to u s e i n

t h e foreground of t h e f oreground/background monitor. A t t h e p r e s e n t time d a t a

cannot be processed wi th the Tektronix 4051 dur ing t h e t i m e it is being

accumulated.

background monitor or write a sub rou t ine to provide communication wi th t h e

4051 between scans.

W e i n t e n d to e i t h e r adapt t h e program to t h e foreground/

29

F i e l d T e s t s of Organic Add i t ives f o r t h e Con t ro l

o f Sca l ing of Hypersal ine Geothermal Br ine

Responsible Personnel: J. E. Harrar, F. E. L o c k e l * L. E. Lorensen: C. H.

O t t o , Jr., S. B. Deutscher, W. P. Frey,**

E. 0. Snell ,** and R. L im

Br i e f Descr ipt ion: Seve ra l compounds were found t h a t s i g n i f i c a n t l y r e t a r d

t h e formation of t h e siliceous scales from t h e b r i n e s

of t h e S a l t o n Sea Geothermal Field. The best o v e r a l l

performance was e x h i b i t e d by a polyethylene imine of

molecular weight -1800 (Corcat P-18, Cordova Chemical

Company).

Status: For the f i n a l test series of t h i s project, a new group of 19

compounds was s e l e c t e d from t h e classes p rev ious ly e s t a b l i s h e d to have high a c t i v i t y as s i l i c a - p r e c i p i t a t i o n inhibitors. I n t h i s group were the following:

0 A series of qua te rna ry ammonium compounds (obtained from Armak) to be compared e s p e c i a l l y wi th Ethoquad 18/25, which was eva lua ted previously. ti

0 A series of polyethylene imines (obtained from Cordova Chemical

Company), some having d i f f e r e n t molecular weights and some having c e r t a i n

other f u n c t i o n a l groups.

0 Three polyaminoethylene hydrochloride sal ts (obtained from Dynapol, ti Inc.) i nc lud ing t h e PAE HC1 t e s t e d previously.

0 A group of miscel laneous qua te rna ry ammonium and polyamine-type

compounds having c e r t a i n f e a t u r e s not p rev ious ly examined.

These compounds were f i r s t evaluated by means of our "s tandard" p r e c i p i t a t i o n

test,17 i n which t h e a d d i t i v e is i n j e c t e d i n t o t h e br ine- t reatment test

system a t 22OoC, samples of e f f l u e n t b r i n e are c o l l e c t e d a t 105OC, and

then the k i n e t i c s of s i l ica p r e c i p i t a t i o n are observed a t 90°C.

* Mechanical Engineering Department, LLL. Organic Materials Divis ion, LLL.

**Metals and Ceramics Divis ion, LLL.

17. J. H. H i l l , J. E. Harrar, C. H. O t t o , Jr., S. B. Deutscher, H. E. Ref. 3 , p. 30.

Crampton, R. G. Grogan, and V. H. Hendricks, Apparatus and Techniques for the Study of P r e c i p i t a t i o n of S o l i d s and Si l ica from Hypersal ine Geothermal Brine, Lawrence Livermore Laboratory, Livermore, CA, UCRL-52799 (1979) .'

30

The m o s t promising of t hese compounds were then subjected t o 40-h s c a l i n g

tests to determine t h e i r e f f e c t i v e n e s s i n r e t a r d i n g t h e scales formed a t 220,

125, and 90°C.

i n t h e p r e c i p i t a t i o n test , we conducted s e v e r a l s c a l i n g tests of combinations

of compounds with complementary f u n c t i o n s which, i t was hoped, would l e a d to

s i g n i f i c a n t r e t a r d a t i o n of scale.

I n a d d i t i o n to s i n g l e compounds shown to be good i n h i b i t o r s

The best compounds found are l i s t ed i n Table 8, and t h e best of t h e s e

appears to be Corcat P-18. I t reduced t h e scales a t 125 and 90°C by factors

of 4 and 1 8 r e s p e c t i v e l y , and it also has a c t i v i t y as a c o r r o s i o n i n h i b i t o r .

PAE-HC1 was not q u i t e a s good a t t h e s e temperatures , b u t it also reduced t h e

scale a t 220°C by a factor of 2-3. Ethoquad 18/25 were mixed; it reduced t h e scale a t 90°C again, b u t not a t

125OC, p o s s i b l y because t h e concen t r a t ion used (35 ppm) was too high.

f o u r t h compound, Mirapol A-15 (a Mirapol Chemical Company po lyd iqua te rna ry

compound), which s t r u c t u r a l l y has a l l of t h e c h a r a c t e r i s t i c s t h a t w e now know

are prerequisites for a n t i s c a l a n t a c t i v i t y , also appeared promising b u t could

not be evaluated thoroughly.

The results ob ta ined t h i s t i m e f o r

A

1 8 A d e t a i l e d report of t h e s e m o s t r ecen t experiments was prepared.

Because both Corcat P-18 and PAE.HC1 are not produced commercially i n l a r g e

q u a n t i t i e s , t hey are r a t h e r expensive. Thus i n t h e near term the most

c o s t - e f f e c t i v e a d d i t i v e formulat ion would probably be a mixture of one of

these s i l i c a - p r e c i p i t a t i o n i n h i b i t o r s and a small amount of hydroch lo r i c

ac id .

s i g n i f i c a n t l y not only augmented, b u t enhanced, t h e r e t a r d a t i o n e f f e c t of t he

s i l ica i n h i b i t o r . W e are also recommending a t h i r d ingredient--a phosphonate

c r y s t a l l i n e - s c a l e inhibitor--which also appears to enhance t h e o v e r a l l

a c t i v i t y of t h e a n t i s c a l a n t mixture even though it does not d i r e c t l y affect

the si l ica.

W e found t h a t an amount of acid i n s u f f i c i e n t to lower t h e b r i n e pH

1 9

18. J. E. Harrar, F. E. Locke , C. H. O t t o , Jr. , L. E. Lorensen, W. P. Frey, and E. 0. S n e l l , On-Line T e s t s of Orqanic Add i t ives f o r t h e I n h i b i t i o n of t he P r e c i p i t a t i o n of S i l i ca from Hypersal ine Brine. IV. F i n a l T e s t s of Candidate Addit ives , Lawrence Livermore Laboratory, Livermore, CA, UCID-18536 (1980).

19. J. E. Harrar, F. E. L o c k e , C. H. O t t o , J r . , L. E. Lorensen, S . B. Deutscher, W. P. Frey, and R. L h , Trans. Geothermal Resources Council , 2 295 (1979).

31

TABLE 8. Three compounds t h a t i n h i b i t s i l i c a s c a l i n g from geothermal b r ine .

structure Chemical name Trade name

-CH2CH2T fHZCH2NH I

CH CH N

2 1 CH2CH2NH2

3 CH3 (CH2) 17-N-CH

I (CH CH +H

x + y = 1 5 2 2 Y . W

h)

NH2* HC1

or

Polyethylene imine m o l w t =: 1800

t

- Methyl c1 polyoxyethylene (15)

octadecylammonium c h l o r i d e

Poly (aminoethylene, HC1 sa l t ) m o l w t =: 120,000

Corcat P-18 (Cordova Chemical Co. )

Ethoquad 18/25 (Armak Chemical)

or 4-18-15

(Tomah Products)

PAE *HC1 (Dynapol, Inc. )

I

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