DISORDERED MATERIAL PHYSICS
DIVISION
Head of Division Dr.hab.phys.D.Millers
Scientific Staff
Solid state radiation physics laboratory Defect
studies group
|
1. Dr. hab.phys. S.Chernov 2. Dr. hab.phys. L.Grigorjeva 3. Dr. hab.phys. D.Millers 4. Dr.phys.V.Pankratov 5. Dr.phys I.Hinoverova 7.
Dr.phys. A.Tale |
1. Dr.hab.phys. A. Silins 2. Dr.hab.phys L. Skuja 3. Dipl. phys. A. Lukjanska solid state optics laboratory 1. Dr.hab.phys., Prof. A.Truhins 2.
Dr.Phys., Dr.Phil. K.Truhins |
Technical Staff Students
1.
2. T. Dudareva
Scientific interests:
time-resolved spectroscopy: optical absorption and luminescence.
Research area:
- the mechanisms of charge self-trapping, retrapping and trapping at different defects/impurities,
- radioluminescence and scintillation mechanisms; energy transfer and storage in solid state;
- physics of luminescent materials for detectors and transformers of ionizing radiation; radiation defects;
- nano-scale phenomena and quantum effects.
Scientific Staff: 3 researchers and 1 student.
At present the research is
focused on the following problems
- mechanisms of charge self-trapping and trapping at different defects/impurities in complex oxides (congruent and stoichiometric LiNbO3; GGG: KNbO3; SrTiO3; SrTiO3:V; SrTiO3:Nb);
- nature and mechanism of scintillation formation in tungstates (CaWO4; ZnWO4; ZnWO4:Fe);
- luminescence processes in nanomaterials, size effects in nanocrystals and ceramics.
Equipment
1. Time-resolved spectroscopy.
1.1. Transient absorption and luminescence under pulsed electron beam excitation:
time resolution 15 ns;
spectral region 0.75 – 5.2 eV;
temperature region 80-420K;
excitation density up to 20 MW/cm2.
1.2. Time-resolved luminescence under laser excitation:
time resolution 10 ns;
spectral region 1.4 – 5.8 eV;
temperature region 80-600K.
2. Steady-state luminescence.
spectra under
x-ray excitation and UV excitation up to 6.2 eV;
luminescence excitation spectra;
dependence of luminescence intensity on temperature;
thermostimulated luminescence after x-ray excitation.
Main results
1.
Experimental and theoretical studies of optical properties of polarons and
excitons in KNbO3 perovskite crystals. Time-resolved absorption and
luminescence spectra have been measured under 10 ns electron beam pulses.
Quantum chemical calculations support the interpretation of the observed
absorption bands at 0.8 eV and 1.1 eV as free electron polarons and bound hole
polarons.
2. Transient colour centres in complex
oxides. The spectra and decay kinetics of transient absorption induced by
pulsed electron beam have been investigated in undoped and Nd-doped Gd3Ga5O12,
YAG, LaGaO3 and others
complex oxide single crystals. It was shown that growth defects and
uncontrolled impurities play a vital part to transient absorption due to F-, F+- and self-trapped O- ñentres.
3. The luminescence center model and the mechanism of luminescence
center formation in ZnWO4, CaWO4, PbWO4 and
CdWO4 tungstate crystals. The
luminescence and induced absorption under pulsed electron beam excitation
(pulse duration 10 ns, 0.26 MeV) were studied. The experimental equipment used
allowed obtaining the transient absorption spectra, luminescence decay kinetics
and transient absorption relaxation times. The luminescence center in two types
of structure modifications (sheelite-type and wolframite) represents a
tungstate-oxygen complex (WO42- in CaWO4 and
PbWO4 and WO66- in ZnWO 4 and CdWO4).
The luminescence is due to self-trapped exciton on the tungstate sublattice.
The precursors for exciton formation are a self-trapped hole (O--
type center) and an electron temporary trapped at W site. The excited state
absorption of the luminescence center was studied. Comparison of luminescence
and induced absorption life-time temperature dependencies gives a strong
evidence that absorption observed in Ca, Pb, Cd and Zn tungstates is due to
electron transition from the luminescence center excited state (exciton) to
some upper state. The transient
absorption from trapped holes and electrons was observed in several tungstates
studied. The delay between electron-hole creation and exciton formation
observed in some tungstates indicates that a large fraction of excitons is not
formed directly from band carriers.
Cooperation:
Latvia:University of Latvia, (Prof. J.Tiliks), University of Latvia, Institute of
Biology (Dr. O.Mutere), SIA “Baltic Scientific Instruments” (Dr.V.Gostillo).
USA: Wake Forest University (Prof. R.T. Williams.)
Czech Republic:Academy of Sciences, Institute of Physics (Dr. M.Nikl), Charles University (Dr.M. Zvara, Dr .P.Hlidek, Dr. J.Bok)
Hungary: Hungarian Academy of Sciences, Research Inst. for Solid State Physics & Optics, Crystal Physics Laboratory (Dr.G.Corradi, Dr.K.Polgar, Dr.A.Watterich, Ph.D.Stud. K.Lenguel)
Poland Polish Academy Institute of Physics University of Rzeszow
Selected papers
1. L.G.Grigorjeva, E.A.Kotomin, D.K.Millers, R.I.Eglitis. The decay kinetics of excitonic luminescence in AgCl crystals. J.Phys.:Condens.Matter. 1995, vol.7, p. 1483 -1491.
2. L.Grigorjeva, D.Millers, E.Kotomin, R.Eglitis, A.Lerman. Optical properties of silver halide fibers: aging effects. J.Phys.D.:Appl.Phys., 1996, vol. 29, p.578-583.
3. D.Millers, L.Grigorjeva, S.Chernov, A.Popov, P.Lecoq, E.Auffray. The temperature dependence of scintillation parameters in PbWO4. Phys.Stat.Sol. (b), 1997,vol.203, p.585-589.
4. D.Millers, S.Chernov, L.Grigorjeva, E.Auffray, I.Dafinei, P.Lecoq, M.Schneegans. Time resolved luminescence and induced absorption in PbWO4 under electron beam irradiation. J.Lumin., 1997, vol.72-74. p.1097-1099.
5. L.Grigorjeva, D.Millers, A.I.Popov, E.A.Kotomin, E.S.Polzik. Luminescence properties of KNbO3 crystals. J.Lumin., 1997, vol.72-74, p.672-674.
6. L.Grigorjeva, D.Millers, E.A.Kotomin, E.S.Polzik. Transient optical absorption in KNbO3 crystals irradiated with pulsed electron beam. Solid State Commun., 1997, vol. 327, , p.104-106.
7. .L.Grigorjeva, R.Deych, D.Millers, S.Chernov. Time resolved luminescence and absorption in CdWO4. Radiation Measurements. 1998, Vol.29, No.3/4, p.267-271,.
8. L.Grigorjeva, D.Millers and V.Pankratov. Luminescence of biexcitons in silver halide crystals. J.Luminescence, 1998, vol.76/77, p.408-410.
9. D.Millers, S.Chernov, L.Grigorjeva and V.Pankratov. The energy transfer to the luminescence centers in PbWO4. Radiation Measurements, 1998, vol.29, No.3/4, p.263-266.
10. L.Grigorjeva, D.Millers, G.Corradi, K.Polgar, V.Pankratov. Induced optical absorption and relaxation process in LiNbO3. Radiation Effects and Defects in Solids, 1999, vol.150, p.193-198.
11. H.M.Yochum, R.T.Williams, V.Nagirnyi, L.Grigorjeva, D.Millers and E.A.Kotomin. Short-pulse excitation and spectroscopy of KTiOPO4, KNbO3 and LiNbO3. Radiation Effects and Defects in Solids. 1999, vol.150, p.271-276.
12. V.Pankratov, L.Grigorjeva, D.Millers, G.Corradi, K.Polgar. Luminescence of ferroelectric crystals LiNbO3 and KNbO3. Ferroelectrics, 2000, v.239, p.241-250.
13. E.Kotomin, R.I.Eglitis, G.Borstel, L.G.Grigorjeva, D.KMillers and V.Pankratov. Theoretical and experimental study of radiation defects in KNbO3 perovskite crystals. Nucl. Instrum. and Methods in Phys. Research, B, 2000, v.166-167, p.239-304.
14.
L. Grigorjeva, D. Millers
15.
D.Millers, S.Chernov,
L.Grigorjeva, V.Pankratov, M. Nikl, Y. Usuki. Luminescence and transient
absorption of doped PWO4 scintillator crystals. Proc. 5th
International Conference on Inorganic Scintillators and their application.
SCINT’99,
16.
R.T. Williams, H.M. Yochum,
K.B.Ucer, D.K. Millers, L.G.Grigorjeva, S.Chernov. Picosecond and nanosecond time-resolved study of luminescence and
absorption of CdWO4 and PbWO4. Proc. 5th
International Conference on Inorganic Scintillators and their application.
SCINT’99,
17. H.M.Yohum, K.B.Ucer, R.T.Williams, L.Grigorjeva, D.Millers, G.Corradi. Subpicosecond laser spectroscopy of blue-light-induced absorption in KNbO3 and LiNbO3. NATO Science Series, 3 High Technology, 2000, v.77, p.125-138.
18. L.Grigorjeva, D.Millers, S.Chernov, V.Pankratov, A.Watterich. Luminescence and transient absorption in ZnWO4 and ZnWO4-Fe crystals. Radiat.Measurem., 2001, v. 33, No.5, p.645-647.
19. L.Grigorjeva, V.Pankratov, D.Millers, G.Corradi, K.Polgar. Transient absorption and luminescence of LiNbO3 and KNbO3. Integrated ferroelectrics, 2001, v.35, p.137-142.
20. O.Muter, D.Millers, L.Grigorjeva, E.Ventina, A.Rapoport. Cr(VI)
sorption by intact and dehydrated Candida utilis cells: differences in mechanisms.
Process Biochemistry, 2001, v. 37, p.505-511.
21. V.Pankratov, D.Millers, L.Grigorjeva, S.Chernov. Transient optical
absorption and luminescence in calcium tungstated crystal. Phys.Stat.Sol.(b), 2001, 225, No.2, R9
22. V.Pankratov, L.Grigorjeva, D.Millers, S.Chernov, A.Voloshinovski. Luminescence center excited state absorption in
tungstates. J. Luminescence, 2001,
v.94-95, p. 427-432.
23. D.Millers, L.Grigorjeva, V.Pankratov, S.Chernov, A.Watterich.
Time-resolved spectroscopy of ZnWO4. Radiat.Effects and Defects in
Solids, 2001, v.155, p.317-321.
24. R.T.Williams, K.B.Ucer, H.M.Yochum, L.Grigorjeva, D.Millers.
G.Corradi. Self-trapped electron and transient defect absorption in niobate and
tungstate crystals. Radiat.Effects and Defects in Solids, 2001, v.155. p.265-276.
25. Yong Qiu, K.B.Ucer, R.T.Williams, L.Grigorjeva, D.Millers,
V.Pankratov. Transient absorption of
polarons in KNbO3. Nucl. Instrum.and Methods in Physics Research, B,
2002, v.191, p.98-101.
26. L.Grigorjeva, D.Millers. The model of recombination process in TlBr. Nucl. Instrum.and Methods in Physics Research. 2002, v.1912, p.131-134.
27. D.Millers, L.Grigorjeva, V. Pankratov, V.A.Trepakov, S.E.Kapphan. Pulsed electron beam excited transient absorption in SrTiO3. Nuclear Instruments and Methods in Physical Research B, 2002, v.194, p 469-473.
The interests of the laboratory cover fundamental research of materials widely used for microelectronics (silicon dioxide films on silicon) and telecommunications (based on silicon dioxide telecommunication fibers).
Research area:
- The electronic excitations,
intrinsic and impurity defects of the ordered materials (crystals) and the
disordered materials (optical glasses).
- The localization due to disorder
states.
- The main approach is experimental
investigations of the optical properties, in general, and luminescence
properties, in particular.
Scientific
staff
includes 2 researchers
At present the research is focused on the following problems:
- Electronic excitations localized
due to electron-phonon interaction (self-trapped) in silicon dioxide,
germanium dioxide and relevant aluminum and gallium orthophosphates in
crystalline and glassy states.
- The static localized states of
short-range order, related to a material isomorphism of wide gap optical
glasses (silicon and germanium dioxide, alkali silicates and germanates). sensitivity of localized states to
history of glass preparation and treatment by light (laser, etc.).
Equipment:
Optical system
for studies of absorption, luminescence and photoelectric properties of
insulators under vacuum ultraviolet irradiation.
Main results:
the excitons in SiO2, GeO2, AlPO4 and GaPO4 crystals with a-quartz structure were identified. A broad excitonic band of intrinsic absorption occurs in these crystals. Its long wavelength tail obeys Urbach's rule. That finding is in a good agreement with the observation of the self-trapped excitons (STE) in these crystals. The low-energy shift of absorption tail observed with the change of Si- to Ge- and of Al- to Ga-containing crystals shows that the exciton of absorption tail is related to cation. The hole part of the exciton is connected to oxygen in all cases, therefore the exciton giving rise to the intrinsic absorption tail corresponds to a charge transfer transition from oxygen 2p to 3(4)d of cation.
The intrinsic absorption band in quartz at 10.45 eV and in berlinite at 9.8 eV is probably caused by a Frenkel exciton localised mainly on oxygen due to 2p-3s states. This exciton interferes with 2p-3(4)d charge-transfer excitons and both interfere additionally with the background (Fano effect) of interband joint states with a small density. In the cases of Ge and Ga it seems that charge transfer excitons develop separate bands, threfore Eo is closer to the band maximum.
The STE in SiO2, GeO2, AlPO4, and GaPO4 crystals with a-quartz structure was found. Only one kind of STE was found in cristobalite, whose structure is different from a-quartz. By contrast, two kinds of STEs were found in SiO2 a-quartz. Initially, they were ascribed to the specific structure of a-quartz. therefore, two types of STE were predicted in others crystals with a-quartz structure as well (GeO2, AlPO4, GaPO4).
Figure 1. Geometric structure of STE in a-quartz for two orientations. a – ground state lattice, a’ – excited state lattice.
Figure 2. MO diagram for STE in a-quartz.
The hole of STE remains on this non-bridging oxygen (NBO), whereas electron remains on diffuse antibonding orbital, Fig.2. The STE sensitivity to medium range order is explained by the forming of bonding between NBO of STE and bonding oxygen (BO) at the opposite side of c or x, y channels in a-quartz structure. Hole is thus distributed between two oxygen atoms. The bonding energy determines STE thermal stability. When electron comes from antibonding states of Si-O to antibonding state between oxygens, the bond between oxygen atoms is destroyed and a normal lattice is restored. The direction of bonding determines luminescence polarization properties.
It was earlier understood solid state
physics that disorder should lead to localization of elementary
excitations. Localized states due to
disorder have obtained an important meaning in physics after
The glass structure can be imagined as many different kinds of structural motifs of short range
order and each motif corresponds to the ability of the material to exist in
different crystalline modifications. Silicon dioxide is characterized by huge
number of modifications (a-quartz, cristobalite, tridimite, stishovite,
koesite, etc.). The main tetrahedron structure in short range order of silica
provides equal possibilities for defect structure in crystal and glass. the most investigated E’-center, or
oxygen vacancy with a hole) possesses very similar properties in crystalline a-quartz and silica
glass. The situation with others defects is different. for example, the oxygen deficient center with corresponding
luminescence bands can not be observed in a-quartz crystal in light irradiation, only after
hard irradiation. The most significant situation is for the case of GeO2.
Strongly oxidized GeO2 glass possesses two intrinsic absorption
tails. One of them, at 6 eV, is the same as in GeO2 crystal with a-quartz structure;
another, at 4.5 eV is similar as in rutile-type structured crystal. The latter
causes luminescence of localized states.
In alkali germanate glasses the properties of localized states are
identical with those of pure GeO2 glasses. The rutile-like structure
provides absorption lowest in energy, but alkali oxide absorption lays at
highest energy.
The situation in
SiO2 is less clear-cut. Possibly, similar absorption of
octahedron-corresponding motifs is situated at higher energy than that of
tetrahedron motifs. Nevertheless, the effect of oxygen deficiency is similar
both for SiO2 and GeO2. So, we relate the 7.6 eV
absorption band to octahedron motifs in short range order, which are affected
by oxygen deficiency.
Figure 3.
Illustration of different ways of luminescence excitation in pure sodium
silicate glass.
The localized
states of sodium silicate glasses are very different from that of sodium
germanate glasses, because sodium oxide absorption lays at lower energy than
silicon dioxide absorption of probably all structural modifications. Therefore
the localized states of sodium silicate glass are well described by Si-O—Na+
elements or L-centers, interacting among themselves. Lone such element is
responsible for luminescence band positions, luminescence polarization, etc. interacting elements are responsible
for huge quantity of radiation effects, Fig.3: color centers, (L- or
E, L+or HC), complex luminescence decay kinetics as well as strange
loss of polarization of luminescence at very low temperatures (below 20 K).
Cooperation:
Education
activities:
Performed courses of lecture “localized
states in wide-gap oxide glasses”
Selected publications:
1.
A.N.Trukhin, Localized states in wide gap glasses. Comparison with relevant crystals. Journal of Non-Crystalline Solids, Vol.189,
pp.1-15, 1995.
2.
A.N.Trukhin, Journal of
Non-Crystalline Solids, Vol.189 pp.291-296, 1995.
3.
B.Poumellec, V.M.Mashinsky,
A.N.Trukhin, and Ph.Guenot, 270 nm
absorption and 432 nm luminescence bands in doped silica glasses. J.
Non-Cryst. Solids, 239, pp. 84-90, 1998.
4.
H.-J.Fitting A.von Czarnowski, A.N. Trukhin, M.Goldberg and T.Barfels, Modification of electronical and optical
properties in SiO2 films by electron beam irradiation, Solid
State Phenomena, Vol.63-64, pp. 333-340, 1998.
5.
A.N. Trukhin, H.-J.
Fitting, T. Barfels, and A. von Czarnowski, Cathodoluminescence and IR absorption of
oxygen deficient silica – influence of
hydrogen treatment, Journal of Non-Crystalline Solids, Vol.260,
pp. 132-140, 1999.
6.
A.N. Trukhin and H.-J. Fitting,
Investigation of optical and radiation
properties of oxygen deficient silica glasses, Journal of Non-Crystalline
Solids, Vol.248, pp.49-64, 1999.
7.
A.N. Trukhin, H.-J.
Fitting, T. Barfels, and A. von
Czarnowski, Cathodoluminescence
and IR absorption of oxygen deficient silica – influence of hydrogen treatment, Radiation
Effects and Defects in Solids, Vol.49, pp.61-68, 1999.
8.
A.Trukhin, B.Poumellec, and J.
Garapon, luminescence decay kinetics of ge related center in silica, Radiation Effects and
Defects in Solids, Vol.149, pp. 89-95, 1999.
9.
H.-J.Fitting, T.Barfels, A. von
Czarnowski, and A.N.Trukhin, Electron
beam induced optical and electrical properties of SiO2, The
European Material Conference (E-MRS 1999 Spring Meeting, Strasbourg, France June
1-4, 1999, p.F-19.
10.
H.-J. Fitting, T.Barfels, A.N.
Trukhin, and B.Schmidt, Cathodoluminescence
of crystalline and amorphous SiO2 and GeO2, J. of
Non-Crystalline Solids Vol.279 pp.51-59, 2001.
11.
H.-J. Fitting, T.Barfels, A.N.
Trukhin, B.Schmidt, A.Gulans, and A. von Czarnowski, Cathodoluminescence of Ge+, Si+, and O+
-implanted SiO2 layers and the role of mobile oxygen in defect
transformation, J. of Non-Cryst. Solids, Vol.303, pp. 218 – 231, 2002.
12.
Jérôme
Garapon, Bertrand Poumellec, S. Vacher, and Anatoly Trukhin, Observation of a new photoluminescence band at 320 nm
under 270 nm excitation in Ge-doped silica glass,
Journal of Non-Crystalline Solids, Vol.311, pp. 83-88, 2002.
13.
Anatoly
Trukhin, Bertrand Poumellec, and Jérôme Garapon, study of the germanium
luminescence in silica: from non-controlled impurity to germano-silicate core
of telecommunication fibers perform, Euro Summer School On Photosensitivity in
Optical Waveguides And Glasses. POWAG 2002, St-Petersburg
Group of
Defects Studies
The general research interests of the Group of Defect Studies concern
glassy/amorphous materials for optics and electronics. The main focus is on
oxide materials based on SiO2 and GeO2. The motivation
for studying these materials is provided by the outstanding physical properties
of glassy SiO2 and the key role it plays in a number of modern
applications: low-loss optical fibers for communications, ultraviolet and
high-power laser optics, insulating oxide layers in silicon-based
microelectronics, radiation resistant optical glasses.
Research
area:
·
Effects of
disordered state on the optical and electronic properties of glassy and
amorphous oxide materials
·
Spectroscopic
properties and structure of point defects in glassy amorphous materials
·
Defect
processes and structural conversions in disordered oxide materials induced by
light, radiation, thermo-chemical treatments or other external factors.
Fundamental objectives: Establishing the structure and generation
processes of point defects in silica-based glasses.
Current applied objectives: glassy materials with high ultraviolet
transparency and high resistance to laser light; glassy materials optimized for
fiber optic Bragg gratings for telecommunication and sensor applications.
The present focus points of the research:
(1) identification of the origins of the additional optical absorption
induced in glassy silicon dioxide induced by light of ArF and F2
excimer lasers.
(2) factors governing the transparency of silica glass in
deep-ultraviolet and vacuum-ultraviolet regions
(3) microstructure and spectroscopic properties of oxygen-excess related
defects in silica
(4) role of hydrogen and fluorine dopants in increasing laser toughness
and transparency of silica
(5) mechanisms of the UV-induced photorefractive Bragg gratings in
silica
Equipment:
- Optical
absorption spectroscopy
- Luminescence
spectroscopy
- Time-resolved
spectroscopy
Main results:
The main result of the Group of Defect Studies is the
spectroscopic identification and model assignments of a number of intrinsic
defects in glassy SiO2 and GeO2, the models of which are
depicted in Fig.1 and Fig2. Among the results on oxygen-excess related defects,
the most important point is the establishing of the optical properties of the
basic disorder-related intrinsic defect in glassy SiO2, the oxygen
dangling bond (Fig.1). This defect is also of major importance to applications
since it dominates the ultraviolet part of the optical absorption spectrum of
glassy SiO2. Additionally, it is one of the most interesting defects
from the viewpoint of fundamental studies, because of the anomalously low
electron-phonon coupling of its low-energy optical transitions. Other
oxygen-related defects identified include interstitial oxygen atoms, which are
incorporated in the glass network in the form of peroxy bridges (Fig.1) and
interstitial oxygen and ozone molecules, which occur in oxygen excess silica
glasses or are formed as intrinsic radiation defects.
Fig.1.
Basic oxygen-excess related defects in glassy SiO2: oxygen dangling bond (non-bridging oxygen
hole center), peroxy radical, interstitial oxygen in the form of a peroxy
bridge (Si-O-O‑Si bond),
interstitial oxygen molecule O2, and interstitial ozone molecule O3. Group of defect
studies has contributed to their identification and to establishing their
optical characteristics.
Fig.2.
Twofold- coordinated silicon defect in
normally (4:2) coordinated SiO2 glass network. The isoelectronic Ge-
based counterpart of this defect is largely responsible for the photosensitivity
of SiO2:GeO2 glasses, which is utilized to create
fiber-optic Bragg gratings for wavelength-divided multiplexing in optical fiber
communication networks.
In oxygen-deficient glasses, the most
important result is the identification of two-coordinated silicon center. This
defect has been a focus point of a long controversy, as it has been previously
associated with oxygen vacancies. In the work of Group of defect studies it was
shown that its optical properties correspond to those of a divalent Si atoms
and that similar Ge- and Sn- based isoelectronic defects occur in Ge- and
Sn-doped SiO2 glasses. The divalent Ge defect is presently widely
used to enable writing of photoinduced refractive Bragg gratings by UV laser
light for processing of optical signals in communication systems.
Apart from original research papers, the
Group of defect studies has originated a number of review papers on defects in
silica and recently co-organized a NATO ASI school on defects in SiO2
and related materials.
Cooperation:
Tokyo Institute of Technology,
Physikalisch-Technische
Chemical Department,
The group takes part in the "
Education
activities:
§
Courses of lectures “Optical properties of
solids” (prof. A.Siliņš) for students of the
Selected publications
1. L.N. Skuja, A.R.Silin, and A.G.Boganov . On the nature of the 1.9 eV luminescence
centers in amorphous SiO2 . J. of Non-Crystalline Solids Vol.63, No3, pp.431-436, 1984.
2. L. N. Skuja,
A. N. Streletsky, and A.B. Pakovich. A
new intrinsic defect in amorphous SiO2 : Twofold
coordinated silicon. Solid State Comm. Vol.50, No12, pp.1069-1072, 1984.
3.
L. N.
Skuja, A.N. Trukhin, and A.E. Plaudis. Luminescence
in germanium- doped glassy SiO2.
Physica Status Solidi
(a), Vol.84, No2, pp.K153-K157, 1984.
4. A. R. Silin and A.N. Trukhin, "Point defects and electronic excitations in
crystalline and glassy SiO2" (in Russian)
5. L. N. Skuja. Photoluminescence of intrinsic defects in glassy GeO2:
Twofold coordinated Ge and non-bridging oxygen. Physica Status Solidi (a)
Vol.114, pp.731-737, 1989.
6. L. Skuja,
Isoelectronic series of twofold coordinated Si, Ge, and Sn atoms in glassy SiO2:
a luminescence study.
J.Non-Crystalline Solids, Vol.149,
pp.77-95, 1992.
7. L. Skuja. Direct
singlet-to-triplet optical
absorption and luminescence
excitation band of the twofold-coordinated silicon center in oxygen-deficient
glassy SiO2. J. Non-Crystalline Solids, Vol.167, pp.229-238, 1994.
8. L. Skuja,
The origin of the intrinsic 1.9 eV luminescence band in glassy SiO2.
J.of Non-Crystalline Solids Vol.179,
pp.51-69, 1994.
9. L. Skuja, T. Suzuki, and K. Tanimura, Site-selective laser spectroscopy studies of
the intrinsic 1.9 eV luminescence center in glassy SiO2. Phys.Rev. B. Vol.52, pp.15208-15216, 1995.
10. L. Skuja, K.Tanimura, and
11. L. Skuja and B. Güttler, Detection of interstitial oxygen molecules
in SiO2 glass by a direct photoexcitation of the infrared
luminescence of singlet O2. Phys.Rev.Letters Vol.77, pp.2093-2096, 1996.
12. L. Skuja, A.
Naber Laser-induced luminescence in glassy SiO2 and
neutron-irradiated alpha quartz: three types of non-bridging oxygen hole
centers. Materials Science Forum, Vol. 239-241,
pp.25-28, 1997.
13. L. Skuja, B. Güttler, D. Schiel, and A. R.
Silin, Quantitative analysis of the
concentration of interstitial O2 molecules in SiO2 glass
using luminescence and Raman spectrometry. J.Appl.Physics Vol.83, No 11, pp.6106-10, 1998.
14.
L. Skuja, The nature of optically active oxygen-deficiency-related
centers in amorphous silicon dioxide. J. Non-Crystalline Solids, Vol.239, No 1-3, pp. 16-48, 1998 (review).
15. L. Skuja, B. Güttler, D. Schiel, and A.
R.Silin, Infrared photoluminescence of
pre-existing or radiation-induced interstitial oxygen molecules in glassy SiO2
and a-quartz. Phys.Rev. B, Vol.58, No21, pp.14296-14304, 1998.
16. M. Mizuguchi, L. Skuja, and H. Hosono, Photochemical processes induced by 157-nm
light in H2-impregnated glassy SiO2:OH. Optics
Letters, Vol. 24, No 13, pp.863-865,
1999.
17. M. Mizuguchi, L. Skuja, H. Hosono, and T. Ogawa
, F-doped
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22. L. Skuja, K. Kajihara, T. Kinoshita, and M.
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