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TitleLight Scattering in Solids: Proceedings of the Second Joint USA-USSR Symposium
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Page 1

Light Scattering in
Solids

Page 2

Proceedings of the Second Joint USA-USSR Symposium

Light Scattering in
Solids

Edited by

Joseph L. Birman and Herman Z. Cummins
Department of Physics

The City College of the City·University of New York
New York, New York

and

Karl K. Rebane
Institute of Physics

Academy of Sciences of the Estonian SSR
Tartu, Estonian SSR

PLENUM PRESS • NEW YORK AND LONDON

Page 262

K.K.REBANE

The conclusions of the theory are in reasonable agreement with
experiments (see an earlier review (19). HL of crystals was first
observed on a sample of KCl-N02 in (20). Afterwards, in the
laser-excited RSE of molecular anions all three components - OL,
HL and RRS are clearly demonstrated: on KI-Se2 by L. Rebane and
T. Haldre (21), on KCl-N02 by P. Saari (23,24). Recently full
RSE spectra were obtained and investigated in the case of mixed
(24) and pure molecular crystals (25); particularly, a rich RSE
spectrum in the strong exciton absorption region of anthracene
shows pecularities caused by polariton effects (26).

The HL studies have provided information on different energy
relaxation pathways and the corresponding characteristic times of
picosecond duration (see review papers (19,25». HL data combined
with the studies of homogeneous linewidths enable to get estimates
for the transverse relaxation times to be obtained as well (27).

3. TIME-DEPENDENT (TRANSIENT) SPECTRA OF RSE

There is quite a number of general problems about
time-dependent spectra such as mathematical definitions of what is
a time-dependent spectrum, and how to take into account the role
of the spectral apparatus when real physical spectra are concerned
(28-31». Recent success in pico- and subpicosecond pulse
experiments requires a corresponding development of theory, and
recently a number of papers on time-dependent RSE spectra of
luminescence centers in crystals has been published (30-33).
Naturally, time-dependent spectra display very clearly how all
three RSE components - scattered light, HL and OL - come into
being after a short-pulse excitation, how the intensities and
shapes of the lines of luminescence develop with the time of
collecting photons and how they depend on the choice of the
collection time interval. The models used in (30,32,34) and
especially in (35-37) by V. Hizhnyakov and I. Rebane are quite
complete for a proper discussion of the problem (see also (38,39».

I shall review some recent results of the theory mentioned
above. The details of the models under study and the
corresponding formulae may be found in (32,34,35,37). Let us give
here the list of the notations and the main features of the models.

The emission center is characterized by a usual potential
energy diagram with two parabolic curves of different curvatures
representing the local vibration in ground and excited electronic
states (Fig. 1). As we know, it is most important to take into
account the vibrational relaxation, without which we cannot get
the correct picture of RSE. Here it is supposed that the n-th
level of the oscillator decays exponentially with the
characteristic time Til ,n = Til ,lin = (Zr11n)-1 (model 1)

Page 263

RESONANT SECONDARY EMISSION BY IMPURITIES IN CRYSTALS 261

Q w"

Fig. 1. The diagram of the potential energy curves and the scheme
of the vibronic resonant secondary emissions lines of an emission
center in a crystal. The transitions and lines of ordinary
luminescence (broad lines), hot luminescence (narrow lines), and
scattered light (dashed lines) are shown. Because of the
different frequencies of vibration in the ground and excited
electronic states the luminescence lines corresponding to
different transitions are separated; owing to the excess of the
excitation energy x over the vibronic level the lines of
scattering are shifted from the luminescence ones (35,37).

Page 523

534

SiC:Ti
exciton bound to isoe1ectronic

trap in, 204
Six-photon process, 462
S~

order parameter, 369
Smectic A (S~) phase, 367
Smectic B (SmB) phase, 373
Smectic liquid crystals, 48
Soft mode, 334
Solvent electron, 417
Solvent induced shift and

broadening, 414
Spatial dispersion, 133
Specific heat ratio, 5
Spectral density of scattered

light, 333
Spectral width, 458
Spectrum

of x-magnons in COC03, 185
of y-magnons in COC03, 185

Spin cluster formation, 195
Spin diffusion, 190

no charge transport, 191
from transverse part of donor

spin exchange, 193
Spin flip cross sections

(2_g)2 rule, 201
Spin flip for free electron

and holes in SiC, 202
Spin flip Raman scattering, 189
Spin flip scattering, 199

with charge diffusion, 189
excitons in SiC, 199

Spin-orbit splitting in traps
in SiC, 205

Spin wave, 177
acoustic branch, 238
optic branch, 238

Spin-wave parameters
COC03, 180
FeB03, 180

Spin-wave relaxation, 181
Spin-wave therma1ization, 183
Spinodal line, 33
Stark shift of resonance

level, 460
Stimulated Raman scattering,

167

SUBJECT INDEX

Stokes/anti-Stokes asymmetry
in bulk spin wave
scattering, 210

Stokes/anti-Stokes correlation,
287

Structural phase transition
imperfect crystals, 331
pure crystals, 331

Structure disorder, 447
Structure factor, 52
Superconducting gap, 347
Super1attices, 308
Surface carrier

bulk phonon coupling, 301
Surface electromagnetic wave, 115
Surface enhanced Raman scattering

499, 504
wavelength dependence, 504

Surface fields
microscopic theory of, 513

Surface plasmon, 500, 504, 511
Surface plasmon damping, 507
Surface plasmon energy of Ag, 505
Surface polariton, 113, 120, 121,

490
scattering at phase-transitions,

126
wedge light diffraction, 124

Surface polariton dispersion, 113,
114

Surface Raman scattering, 483
matrix elements for, 507

Surface roughness, 126, 480
of metal, 483
and photon coupling, 505

Surface spin-wave
angular anisotropy, 209
dispersion of, 209

Surface waves, 119
Swelling of gels, 31
TI and T2 relaxation, 321
TaSe2 (2H)~ 34~
Tay10r-Couette flow, 24
Taylor vortex pattern, 16
Thermal conductivity above

A point, 8
Thermal diffusivity

E expansion, 9
Thermal radiation

odd moments, 290

Page 524

SUBJECT INDEX

Thermalized luminescence from
real states, 216

Thick films
critical behavior, 39

Three-photon scattering, 460
Three-wave Raman scattering

in diamond, 428
Tilted molecules, 53
Time resolved CARS

molecular crystals, 447
Time resolved Raman scattering,

403
Transient pulse propagation,

133
Transient reflection, 133
Transient reflectivity, 131
Transient in scattering and

luminescence, 321
Transient spectra, 260

oscillating structure, 264
Transverse collective resonance

of electrons, 491
Triangular lattice

melting, 49
Tunnel hot luminescence, 278
Turbulence, 15, 17, 20, 23
Two-magnon production by

photon, 183
Two-phonon processes, 363
Two-phonon resonant Brillouin

scattering, 148
A exciton in CdS, 154

Two-photon absorption in RbBr,
431

Two-photon Kirchoff law, 289
2,6-lutidine, 39
2 + 2' scattering, 150
Universality

turbulence, 25
Vapor deposition of molecules

on metals, 484
Velocity power spectrum, 18, 21
Vibrational relaxation, 260
Vibrational spectrum of

monolayer, 167
Vibrations

bending and stretching, 74
Vibrons, 448
Visual pigments, 391

S3S

Vortex pattern, 15
Vortices and disclination pairs,

51
Wurtzite, 150
X-ray scattering from SmA, 368
Zeeman splitting, 101
ZnTe:Na, 200

electron and hole spin
flip in, 200

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