9/15/04 B. Azmoun 1

Transmittance as a Function of Water and Oxygen Levels in the

VUV Regime

Bob Azmoun, Brookhaven National Lab

2

ApparatusInjecting ppm’s of H2O

Injecting ppm’s of O2

VUV Spectrometer

Micrometer Valve

Micrometer Valve

~15psig

~15psig

Bubbler filled with pure distilled water

Mass Flow Controller

Mass Flow Controller

~2psi over-pressure

~2psi over-pressure

H2O/O2Analyzer

H2O/O2Analyzer

Pressure Controller

Pressure Controller

Vent

Vent

3

ResultsTransmittance in 36cm of Ar Vs PPM 's of O2

0

10

20

30

40

50

60

70

80

90

100

110

1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Wavelength [Angstroms]

% T

ran

smit

tan

ce [

%]

[O2]=0.43ppm [H2O]=9.8ppm

[O2]= 0.60ppm [H2O]=11.32ppm

[O2] = 4.5ppm [H2O] = 21.1ppm

[O2]=9.9ppm [H2O]=12.8ppm

[O2]=18.3ppm [H2O]=18.0ppm

[O2]=26.8ppm [H2O]=16.9ppm

[O2] = 45.4ppm [H2O] = 14.8ppm

[O2]=60.0ppm [H2O]=18.4ppm

[O2]=83.5ppm [H2O]=18.0ppm

[O2]=111.0ppm [H2O]=12.5ppm

[O2]=150.5ppm [H2O]=14.4ppm

[O2]=350.0ppm [H2O]=20.0ppm

[O2]=476.0ppm [H2O]=15.12ppm

Calibrated M ix: Ar/O2(10.3ppm), [O2]=12.6ppm [H2O]=18.8ppm

Calibrated M ix: Ar/O2(50.3ppm),[O2]=57.9ppm [H2O]=15.5ppm

Transmittance in 36cm of Ar Vs PPM 's of H2O

0

10

20

30

40

50

60

70

80

90

100

110

1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Wavelength [Angstroms]

% T

rans

mitt

ance

[%]

[O2]=0.43ppm [H2O]=9.8ppm

[O2] = 0.63ppm [H2O]=11.32ppm

[O2]=0.48ppm [H2O]=22.45ppm

[O2]=0.03ppm [H2O]=38.25ppm

[O2]=0.60ppm [H2O]=57.5ppm

[O2]=2.5ppm [H2O]=118.0ppm

[O2]=0.35ppm [H2O]=206.80ppm

[O2]=0.06ppm [H2O]=317.5ppm

Reference: Attenuation Coefficient for O2 Reference: Interaction Cross Sect. for H2O

4

Integrated Transmittance

Integrated Transmittance: 1120 - 2000 Angstroms

0

10

20

30

40

50

60

70

80

90

100

110

0 50 100 150 200 250 300 350 400 450 500

PPM's [ppm]

Inte

gra

ted

Tra

ns

mit

tan

ce

ov

er

VU

V

sp

ec

tru

m

H2O

O2

Calibrated Ar/O2 Mix([O2]=10.3, 50.3ppm nominal)

5

Level of agreement with results found in the prevailing literature

Transmittance @ 1450 Angstroms Vs PPM 's of O2 thru 36cm of Ar

0

10

20

30

40

50

60

70

80

90

100

110

0 50 100 150 200 250 300 350 400 450 500 550

[O2] [ppm]

Tran

smitt

ance

@14

50 A

ngst

rom

s

[%]

Data

Calibrated Ar/O2 Mix([O2]=10.3, 50.3ppm nom inal)

From Reference

T = exp-(NLp) = exp-(Kp)

Transmittace @ 1290 Angstroms Vs PPM's of H2O thru 36 cm of Ar

0

10

20

30

40

50

60

70

80

90

100

110

0 50 100 150 200 250 300 350 400 450 500 550 600

[H2O] [ppm ]

Tran

smitt

ance

@ 1

290

Ang

stro

ms

[%]

Data

From Reference

6

Conclusions• The results above have been verified by two independent sources

• Interaction X-sect. for H2O & Attenuation Coefficient for O2

from literature, and two transmittance measurements using two

bottles of Ar with calibrated levels of O2

• In order to preserve roughly 95% of light in the range from 1120-

2000 Angstroms, the water vapor and O2 concentrations must kept

below 10 and 15ppm’s respectively within the gas(for a 36cm gas

absorber)