detection of defects in minerals by luminescence spectroscopy · luminescence of inorganic and...
TRANSCRIPT
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
300 400 500 600 700 800 900 1000 1100
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Sm3+
Eu2+
Sm3+
Nd3+
Dy3+
Detection of defects in minerals by
luminescence spectroscopy
Detection of Detection of defects defects in in minerals by minerals by
luminescence spectroscopyluminescence spectroscopyJens Götze
TU Bergakademie Freiberg
1. Physical basics of luminescence phenomena
2. Defects in minerals and the luminescence signal
3. Factors influencing the luminescence properties of minerals- typomorphic properties (quartz)- crystal chemistry (feldspar minerals)- aspects of quantitative luminescence spectroscopy
4. Conclusions
ContentContent
Physical basics of luminescence phenomena
Physical basics of luminescence phenomena
???
LuminescenceLuminescence
= transformation of diverse kinds of energyinto visible light
Basics of luminescence
Luminescence of inorganic and organic substances
results from an emission transition of anions, molecules
or a crystal from an excited electronic state to a ground
state with lesser energy.
(Marfunin1979)
Basics of luminescence
Main processes of luminescence
(1) absorption of excitation energy and stimulationof the system into an excited state
(2) transformation and transfer of the excitation energy
(3) emission of light and relaxation of the systeminto an unexcited condition
Schematic model of luminescence processes
Excitationby energy
Emissionof light
e-
biological processes bioluminescence
thermal excitation
electrons
UV photoluminescence
thermoluminescence
cathodoluminescence
Basics of luminescence
The band modelThe band model
Basics of luminescence
valence band
conduction band
insulatorconductor semiconductor
E
Energy levels in a band scheme for different crystal types
band gap
band gap
insulator
E (photonenergy)
Basics of luminescence
Valence band
E
luminescence
(a) (b) (c)
activator
trap
(d)
Conduction band21
Basics of luminescence
intrinsic luminescence
radiatio nlesstransition
extrinsic luminescence
The configurational coordinatemodel
The configurational coordinatemodel
Basics of luminescence
Basics of luminescence
excitedstate
groundstate
Configurational coordinate diagram for transitions according to the Franck-Condonprinciple with related absorption and emission bands, respectively.(modified after Yacobi & Holt 1990)
absorptionband
emissionband
Basics of luminescence
Excitation (1) and emission (2) spectra of Mn2+ in calcite (after Medlin 1964)
1
2
Stokes shift
???
Defects in minerals and theluminescence signal
Defects in minerals and theluminescence signal
(2) Luminescence spectroscopy(1) Luminescence microscopy
contrasting of different phases
visualization of defects, zoningand internal structures of solids
oapatite
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
300 400 500 600 700 800 900 1000 1100
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Sm3+
Eu2+
Sm3+
Nd3+
Dy3+
determination of the real structure
detection of defects, trace elementstheir valence and structural position
Detection of the „real structure“ (defect structure)
cc
Importance of spatially resolved analyses !
Defects in minerals and the luminescence signal
Luminescence centres
transition metal ions (e.g., Mn2+, Cr3+, Fe3+)
rare earth elements (REE2+/3+)
actinides (especially uranyl UO22+)
heavy metals (e.g., Pb2+, Tl+)
electron-hole centres (e.g., S2-, O2
-, F-centres)
crystallophosphores of the ZnS type (semiconductor)
more extended defects (dislocations, clusters, etc.)
extrinsic
intrinsic pure lattice defects(broken bonds, vacancies)
trace elements(Mn2+, REE2+/3+, etc.)
Defects in minerals and the luminescence signal
activator
ligands
The crystal field theoryThe crystal field theory
Factors of the crystal field influence(crystal field splitting ∆ or 10Dq):
- type of the activator ion (size, charge, electron configuration)
- type of the ligands
- the interaction distance
- local symmetry of the ligand environment, etc.
(Burns, 1993)
the stronger the interaction of the activator ion with the lattice,the greater are the Stokes shift and the width of the emission line
local environment of the activator ion
Defects in minerals and the luminescence signal
300 400 500 600 700 800
wavelength [nm]
0
16000
12000
8000
4000
rel.
inte
nsity
[cou
nts]
zircon
Dy3+
Dy3+
Dy3+
Dy3+
zircon
scheelite
anhydrite
calcite
fluorite
apatite400 500 600 700 [nm]
Dy3+
Tb3+
Dy3+ Sm3+Dy3+
Sm3+
Sm3+
Sm3+
Tm3+
Influence of the crystal field on luminescence emission spectraInfluence of the crystal field on luminescence emission spectra
(1) influence of the crystal field = weak
CL emission spectra are specificof the activator ion
CL spectra of narrow emissionlines (e.g. REE3+)
Defects in minerals and the luminescence signal
Influence of the crystal field on luminescence emission spectraInfluence of the crystal field on luminescence emission spectra
(2) influence of the crystal field = strong
CL emission spectra are specificof the host crystal
CL spectra of broad emissionbands (e.g. Mn2+, Fe3+)
Mn2+calcite
300 400 500 600 700 800wavelength [nm]
100
400
300
200
rel .
inte
n si ty
[co u
n ts]
Mn2+ activated CL of CaCO3:
aragonite green (~560 nm)
calcite yellow-orange (~610 nm)
magnesite red (~655 nm)
Defects in minerals and the luminescence signal
plagioclase
Fe3+Mn2+
0
800
600
400
200rel.
inte
nsity
[cou
nts]
300 400 500 600 700 800 900wavelength [nm]
750
740
730
720
710
700
690
680
wav
elen
gth
[nm
]0 20 40 60 80 100
An content [mol-%]
Position of the Fe3+ activated CL emission band in plagioclases in relation to theanorthite content
IRredlunar plagioclases
Defects in minerals and the luminescence signal
Influence of the crystal field on luminescence emission spectraInfluence of the crystal field on luminescence emission spectra
Factors influencing the luminescence properties of minerals
Factors influencing the luminescence properties of minerals
Mineral groups and minerals showing CLMineral groups and minerals showing CL
in general all insulators and semiconductors
elements diamondsulfides sphaleriteoxides corundum, cassiterite, periclasehalides fluorite, halitesulfates anhydrite, alunitephosphates apatitecarbonates calcite, aragonite, dolomite, magnesitesilicates feldspar, quartz, zircon, kaolinite
technical products (synthetic minerals, ceramics, glasses !)
Minerals show characteristic luminescence properties in dependence on their specific conditions of formation.
Factors influencing the luminescence properties of minerals
1. Typomorphic properties1. Typomorphic properties
close relationship between specific conditions of quartz formation, real structure and luminescence properties of quartz may provide important genetic information
Quartz (SiO2)Quartz (SiO2)
Real structure of quartzReal structure of quartz
one-dimensional point defects(1) defects of trace elements(2) pure lattice defects
dislocations (two-dimensional)
three-dimensional fluid andmineral inclusions
defects in thecrystal structure
„fingerprints“ of theformation history
SiO4-tetrahedra
OO O
O
Si
Detection of defects by Electron Spin Resonance (ESR)Luminescence Spectroscopy
Real structure of quartzReal structure of quartz
Paramagnetic defects in quartzParamagnetic defects in quartz
(Plötze 1995)
Characteristic CL emission bands in quartz (modified after Götze et al. 2001)Characteristic CL emission bands in quartz (modified after Götze et al. 2001)
Emission Suggested activator References
175 nm (7.3 eV) intrinsic emission of pure SiO2 Entzian & Ahlgrimm (1983)
290 nm (4.28 eV) oxygen vacancy Jones & Embree (1976)
330-340 nm oxygen vacancy Rink et al (1993)(3.75-3.6 eV) [AlO4/Li+] centre Demars et al. (1996)
[TiO4/Li+] centre Plötze & Wolf (1996)
380-390 nm [AlO4/M+] centre; M+= Li+, Na+, H+ Alonso et al. (1983)(3.2-3.1 eV) [H3O4]0 hole centre Young & McKeever (1990)
450 nm (2.8 eV) self-trapped exciton (STE) Stevens Kalceff & Phillips (1995)
470-500 nm extrinsic emission Itoh et al. (1988)(2.6-2.45 nm) [AlO4 /M+]0, GeO4/M+]0 centres McKeever (1984), Götze et al. (2004)
580 nm (2.1 eV) E‘ centre (oxygen vacancy) Rink et al. (1993); Götze et al. 1999)
620-650 nm nonbridging oxygen hole centre (NBOHC) Siegel & Marrone (1981)(1.97-1.9 eV) with several precursors Stevens Kalceff & Phillips (1995)
705 nm (1.7 eV) substitutional Fe3+ Pott & McNicol (1971)
visi
ble
UV
Quartz from rhyolite, Thunder Bay (Canada)
450 nm and 650 nm CL emission bands450 nm and 650 nm CL emission bands
0
500
1000
1500
2000
2500
300 400 500 600 700 800
wavelength [nm]re
l. in
tens
ity [c
ount
s]
2
1
2
1
300 µm
most common CL emissions in igneous quartz
Rochlitz 400 µm
Radiation halos in quartz grains of the U/Au deposit Witwatersrand, RSA
900
1000
1100
1200
1300
1400
300 400 500 600 700 800 900
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Witwatersrand
blue core
violet
orangerim
300 µm
Characteristic CL emission bands in quartz (modified after Götze et al. 2001)Characteristic CL emission bands in quartz (modified after Götze et al. 2001)
Emission Suggested activator References
175 nm (7.3 eV) intrinsic emission of pure SiO2 Entzian & Ahlgrimm (1983)
290 nm (4.28 eV) oxygen vacancy Jones & Embree (1976)
330-340 nm oxygen vacancy Rink et al (1993)(3.75-3.6 eV) [AlO4/Li+] centre Demars et al. (1996)
[TiO4/Li+] centre Plötze & Wolf (1996)
380-390 nm [AlO4/M+] centre; M+= Li+, Na+, H+ Alonso et al. (1983)(3.2-3.1 eV) [H3O4]0 hole centre Young & McKeever (1990)
450 nm (2.8 eV) self-trapped exciton (STE) Stevens Kalceff & Phillips (1995)
470-500 nm extrinsic emission Itoh et al. (1988)(2.6-2.45 nm) [AlO4 /M+]0, GeO4/M+]0 centres McKeever (1984), Götze et al. (2004)
580 nm (2.1 eV) E‘ centre (oxygen vacancy) Rink et al. (1993); Götze et al. 1999)
620-650 nm nonbridging oxygen hole centre (NBOHC) Siegel & Marrone (1981)(1.97-1.9 eV) with several precursors Stevens Kalceff & Phillips (1995)
705 nm (1.7 eV) substitutional Fe3+ Pott & McNicol (1971)
visi
ble
UV
Quartz from pegmatite, Brattekleiv (Norway)
500 nm CL emission band (transient CL)500 nm CL emission band (transient CL)
0
2000
4000
6000
8000
10000
12000
300 400 500 600 700 800
wavelength [nm]re
l. in
tens
ity [c
ount
s]
quartz of pegmatiteBrattekleiv, Norway
initial
final
initial
after100 s
400 µm
most common CL emission in pegmatitic quartz(hydrothermal quartz)
Characteristic CL emission bands in quartz (modified after Götze et al. 2001)Characteristic CL emission bands in quartz (modified after Götze et al. 2001)
Emission Suggested activator References
175 nm (7.3 eV) intrinsic emission of pure SiO2 Entzian & Ahlgrimm (1983)
290 nm (4.28 eV) oxygen vacancy Jones & Embree (1976)
330-340 nm oxygen vacancy Rink et al (1993)(3.75-3.6 eV) [AlO4/Li+] centre Demars et al. (1996)
[TiO4/Li+] centre Plötze & Wolf (1996)
380-390 nm [AlO4/M+] centre; M+= Li+, Na+, H+ Alonso et al. (1983)(3.2-3.1 eV) [H3O4]0 hole centre Young & McKeever (1990)
450 nm (2.8 eV) self-trapped exciton (STE) Stevens Kalceff & Phillips (1995)
470-500 nm extrinsic emission Itoh et al. (1988)(2.6-2.45 nm) [AlO4 /M+]0, GeO4/M+]0 centres McKeever (1984), Götze et al. (2004)
580 nm (2.1 eV) E‘ centre (oxygen vacancy) Rink et al. (1993); Götze et al. 1999)
620-650 nm nonbridging oxygen hole centre (NBOHC) Siegel & Marrone (1981)(1.97-1.9 eV) with several precursors Stevens Kalceff & Phillips (1995)
705 nm (1.7 eV) substitutional Fe3+ Pott & McNicol (1971)
visi
ble
UV
Hydrothermal quartz, Freiberg (Germany)
390 nm CL emission band (transient CL)390 nm CL emission band (transient CL)
most common CL emission in hydrothermal quartz(also synthetic quartz !)
initial
after 60s
300 µm
0
2000
4000
6000
8000
10000
12000
300 400 500 600 700 800
wavelength [nm]re
l. in
tens
ity [c
ount
s]
initia l
finalafter 60s
Initial cathodoluminescence signal and spectralemission after 60 s of electron irradiation
Characteristic CL emission bands in quartz (modified after Götze et al. 2001)Characteristic CL emission bands in quartz (modified after Götze et al. 2001)
Emission Suggested activator References
175 nm (7.3 eV) intrinsic emission of pure SiO2 Entzian & Ahlgrimm (1983)
290 nm (4.28 eV) oxygen vacancy Jones & Embree (1976)
330-340 nm oxygen vacancy Rink et al (1993)(3.75-3.6 eV) [AlO4/Li+] centre Demars et al. (1996)
[TiO4/Li+] centre Plötze & Wolf (1996)
380-390 nm [AlO4/M+] centre; M+= Li+, Na+, H+ Alonso et al. (1983)(3.2-3.1 eV) [H3O4]0 hole centre Young & McKeever (1990)
450 nm (2.8 eV) self-trapped exciton (STE) Stevens Kalceff & Phillips (1995)
470-500 nm extrinsic emission Itoh et al. (1988)(2.6-2.45 nm) [AlO4 /M+]0, GeO4/M+]0 centres McKeever (1984), Götze et al. (2004)
580 nm (2.1 eV) E‘ centre (oxygen vacancy) Rink et al. (1993); Götze et al. 1999)
620-650 nm nonbridging oxygen hole centre (NBOHC) Siegel & Marrone (1981)(1.97-1.9 eV) with several precursors Stevens Kalceff & Phillips (1995)
705 nm (1.7 eV) substitutional Fe3+ Pott & McNicol (1971)
visi
ble
UV
Agate from Chemitz (Germany)
580 nm CL emission band580 nm CL emission band
400 µm
Hydrothermal quartz, Neves Corvo (Portugal)
most common CL emission in hydrothermal quartz
850
900
950
1000
1050
300 400 500 600 700 800
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Pol
secondary
primary
0
10000
20000
30000
40000
300 400 500 600 700 800 900 1000
wavelength [nm]
rel.
inte
nsity
[cou
nts]
transient blue CL
0
5000
10000
15000
20000
25000
300 400 500 600 700 800
wavelength [nm]re
l. in
tens
ity [c
ount
s] yellow CL
Dadoxylon sp.
Primary (yellow CL) and secondary(transient blue CL) silicificationin petrified wood remains fromChemnitz, Germany
quartz sand Camh Rhan quartz sand Haltern
Use of quartz CL colours for evaluatingthe provenance of clastic sediments
200 µm200 µm
met vol
ign
single source mixed source
ign
Quartz is one of the purest minerals(used as a standard material)
but
it may show very different luminescence behaviour !
2. Crystal chemistry2. Crystal chemistry
LiAl Al
FeTi
Ge
Na
K
Factors influencing the luminescence properties of minerals
Incorporation of activator elements andluminescence behaviour depend on:
1. crystallographic factors
2. specific physico-chemical conditions of crystallisation
800
1200
1600
2000
2400
2800
300 400 500 600 700 800 900 1000wavelength [nm]
rel.
inte
nsity
[cou
nts]
Sm3+Eu2+ Dy3+
Dy3+
Sm3+
Sm3+
Nd3+
Sm3+
0
10000
20000
30000
300 400 500 600 700 800
wavelength [nm]
rel.
inte
nsity
[cou
nts]
initial
final
Mn2+
Svenskenalkaline rock
Ehrenfriedersdorfgranite
Luminescence behaviour of apatite from different geological environments
Feldspar mineralsFeldspar mineralsT site: SiO4/AlO4
tetrahedra
M site: cations(K,Na,Ca,Ba)
Substitution:T site: Fe, Ti, Ga, B, Ge, P, Be, Sn, AlSiPM site: Sr, Ba, Li, Rb, Mn, Cu, Pb, Tl, REE, NH4
MT4O8 alumosilicates
K-Na-Ca series
Ca[Al2Si2O8]anorthite
K[AlSi3O8] sanidineorthoklasemicrocline
Na[AlSi3O8]albite
plagioclase
alka
li fel
dspa
r
Defect centres in feldspar minerals (after Petrov 1994)Defect centres in feldspar minerals (after Petrov 1994)
Thermal stable centres
cations Fe3+ and Mn2+ with d5 electron configuration
Thermal matastable centres(reactivation by natural or artificial irradiation)
cations with uncommon valence (Ti3+, [Pb-Pb]3+)anions with uncommon valence (several types of O- defects)BOm
n radicals (SiO33-, SiO3
3-/Al, PO32-, NO2)
organic radicals (C2H5, CH3)
Most frequent centres responsible for CL in natural feldspars:
O- defects and Mn2+, Fe3+
redox conditions
plagioclase
microcline(amazonite)
Luminescence emissions and associated activators in feldsparsLuminescence emissions and associated activators in feldspars
Activator colour Peak Method Reference
Tl+ UV 280 nm PL Gorobets et al. (1989)
Pb2+ UV 280 nm TL Tarasshchan et al. (1975)
Ce3+ UV 355 nm CL Laud et al. (1971)
Eu2+ blue 420 nm CL,TL,RL Mariano & Ring (1975), Jaek et al. (1996)
Cu2+ blue 420 nm CL,TL,RL Mariano & Ring (1975), Jaek et al. (1996)
Al-O--Al blue 450-480 nm CL,TL,RL Marfunin (1979), Walker (1985)
O--Si...M+ bluish-green 500-510 nm TL,RL Marfunin & Bershov (1970)
Mn2+ yellow 550-570 nm CL,TL Sippel & Spencer (1970)
Fe3+ red/IR 690-740 nm CL,TL,RL Sippel & Spencer (1970), Götze et al. (2000)
REE3+ UV-vis-IR several peaks CL Mariano et al. (1973), Götze et al. (2000)
Pb+ ? IR ~860 nm CL, RL Trautmann et al. (1999), Erfurt (2003)IR
visi
ble
UV
orthoclaseBodenmais
0
2000
4000
6000
8000
10000
12000
14000
300 400 500 600 700 800 900wavelength [nm]
rel.
inte
nsity
[cou
nts]
Al-O--Al
Si-O-...M2+
Fe3+
OrthoclaseBodenmais (Germany)
CL of feldspar mainly activatedby electron defectsCL of feldspar mainly activatedby electron defects
Albite (Khaldzan Buregte, Mongolia)
0
10000
20000
30000
40000
50000
60000
300 400 500 600 700 800 900 1000 1100
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Fe3+
Fe3+ activated CL in feldsparFe3+ activated CL in feldspar
o
700
710
720
730
740
0 20 40 60 80 100
Or content in mol-%
peak
-wav
elen
gth
in n
m
680
690
700
710
720
730
740
750
0 20 40 60 80 100
An content in mol-%
peak
-wav
elen
gth
in n
malkali feldsparterrestrial plagioclaseslunar plagioclases
Shift of the Fe3+ emission in alkali feldspars and plagioclasesin dependence on the chemical composition
Shift of the Fe3+ emission in alkali feldspars and plagioclasesin dependence on the chemical composition
Mn2+ activated CLin feldsparMn2+ activated CLin feldspar
0
5000
10000
15000
20000
300 400 500 600 700 800 900
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Mn2+
celsiane, Big Creek
0
1000
2000
3000
4000
300 400 500 600 700 800 900
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Mn2+ Fe3+
1
o2
anorthite, Monzoni
o1
400 µm
0
1000
2000
3000
4000
5000
6000
300 400 500 600 700 800 900
wavelength [nm]
rel.
inte
nsity
[cou
nts]
2
Fe3+
Changes in Mn2+ and Fe3+
incorporation into feldspardue to varying physico-chemicalconditions of crystallisation
Detection of alteration processes in feldspar(REE3+ activated luminescence)
oo 2
1
300 µm
Pol
albite, Spruce Pine (USA)
850
900
950
1000
1050
1100
1150
300 400 500 600 700 800 900 1000 1100
r el .
int e
nsi ty
[cou
nts ]
wavelength [nm]
Dy3+
Nd3+
Dy3+ Sm3+
Sm3+
violet CL800
1000
1200
1400
1600
1800
2000
300 400 500 600 700 800 900 1000 1100
rel.
inte
nsity
[ cou
nts]
wavelength [nm]
green CL
Mn2+
18.3 ppm Mn 1.3 ppm Mn
3. Aspects of quantitative luminescence spectroscopy3. Aspects of quantitative luminescence spectroscopy
Factors influencing the luminescence properties of minerals
Factors influencing the luminescence properties/intensityFactors influencing the luminescence properties/intensity
???!!!
sample preparation
analytical conditions(excitation, temperature, etc.)
type of equipment
analytical factors
time(especially transient luminescence)
quenching(e.g. quencher elements - Fe,
concentration quenching)
luminescence activation
sensitizing
crystalllographic factors
0
1000
2000
3000
4000
5000
6000
7000
400 500 600 700 800
wavelength [nm]
rel.
inte
nsity
[cou
nts]
Mn2+
3
2
1
Mn2+ activated CL in calcite
300 µm
oo o3 1 2
Luminescence activation
Correlation of results of quantitative CL with PIXE for the Mn content in carbonates
(Götte & Richter 2004)
Luminescence activation
Mn2+ activated CL in lunar plagioclases
0
500
1000
1500
2000
300 400 500 600 700 800wavelength [nm]
rel.
inte
nsity
[cou
nts]
o
o
o
o2
4
1
3
2
1
4
3
Luna 24 200 µm
Mn2+
Fe3+Al-O--Al
zone 1 - 7 ppm Mnzone 2 - 31 ppm Mnzone 3 - 23 ppm Mnzone 4 - 14 ppm Mn
Luminescence activation
SyntheticSynthetic dopeddoped feldsparfeldspar samplessamples ((plagioclaseplagioclase AnAn5050))
0
50000
100000
150000
200000
250000
300000
350000
300 400 500 600 700 800 900
wavelength [nm]
inte
nsity
[cou
nts]
1000 ppm
5000 ppm
10000 ppm
Mn2+
Intensity of the Mn2+ activated CL in dependence on the Mn content in feldspar
10
8
6
4
2
0
Inte
nsity
/ a.
u.
0 20 40 60 80 100 120 140 160Mn content [ppm]
plagioclases
alkali feldspar
rel.
CL
inte
nsity
mol-% Mn0 0.5 1.0 1.5
Luminescence activation
excitationemission
activatoractivator
excitationradiationlesstransition
luminescence emission concentration quenching
Luminescence quenching
ConclusionsConclusions
ConclusionsConclusionsAs ideal crystal structures practically do not exist, the properties of minerals are determined by their real structure
Luminescence spectroscopy may provide complex information about the defect structure of solids
importance of spatially resolved spectroscopy
There is a close relationship between specific conditionsof mineral formation or alteration, the defect structure and the luminescence properties („typomorphism“)
problem of standardization
For the interpretation of luminescence spectra it is necessary to consider several analytical and crystallographic factors, which influence the luminescence signal