Far-Infrared Properties of Solids: Proceedings of a NATO Advanced Study Institute, held in Delft, Netherland, August 5–23, 1968

612 Pages·1970·26.23 MB·English

by  S. S. Mitra, S. Nudelman (auth.)

Far-Infrared
Properties of Solids
Optical Physics and Engineering
Series Editor: William L. Wolfe
Optical Sciences Center
University of Arizona
Tucson, Arizona
1968:
M. A. Bramson
Infrared Radiation: A Handbook for Applications
1969:
S.Nudelmanand S. S. Mitra) Editors
Optical Properties of Solids
1970:
S. S. MitraandS. Nudelman,Editors
Far-Infrared Properties of Solids
In preparation:
L. Bi berman and S . Nudelman, Editors
Photoelectronic Imaging Devices
Vol. 1: Physical Processes and Methods of Analysis
Vol. 2: Devices and Their Evaluation
Far-Infrared
Properties of Solids
Proceedings of a NATO Advanced Study Institute,
held in Delft, Netherlands, August 5-23, 1968
Edited by
S. S. Mitra and S. Nudelman
Department of Electrical Engineering
University of Rhode Island
Kingston, Rhode Island
9:>
PLENUM PRESS • NEW YORK - LONDON • 1970
Library of Congress Catalog Card Number 78-122627
ISBN-13: 978-1-4684-1865-1 e-ISBN-13: 978-1-4684-1863-7
DOl: 10.1007/978-1-4684-1863-7
@ 1970 Plenum Press, New York
Softcover reprint of the hardcover lst edition 1970
A Division of Plenum Publishing Corporation
227 West 17th Street, New York, N.Y. 10011
United Kingdom edition published by Plenum Press, London
A Division of Plenum Publishing Company, Ltd.
Donington House, 30 Norfolk Street, London W.C.2, England
All rights reserved
No part of this publication may be reproduced in any form
without written permission from the publisher
PREFACE
This book provides an account of modern aspects relating far
infrared radiation to properties of solids; it encompasses both
theoretical and experimental considerations. Written at the gradu
ate level, it attempts a threefold purpose; an indication of the
breadth of the subject, an in-depth examination of important areas,
and reference material to complement a text for a course.
The treatment and organization of material here is compatible
with a preceding volume of this series on "Optical Properties of
Solids." Chapters 1-6 present material concerned principally with
experimental considerations necessary to the carrying out of meas
urements in the far infrared spectral region. They also serve to
provide considerable introductory material for the remaining chap
ters which deal with various areas that offer theoretical treat
ments utilizing and understanding far infrared properties of solids.
Several lectures presented at the Institute could not be in
cluded in this book for two reasons: (i) Final versions of the
lecture notes suitable for publication never arrived from several
lecturers; (ii) Some materials were deliberately left out fro~ this
book as they were also presented at an earlier NATO Institute and
form part of a preceding volume edited by us in this series. In
particular, it is recommended that Chapters 14 and 15, viz., in
frared and Raman spectra due to lattice vibrations by S. S. Mitra
and impurity induced lattice absorption by L. Genzel in "Optical
Properties of Solids'· be read concurrently with the present volume.
We are indebted to many peoples the authors for their effort
and patience; our host, the Governors and Senate of the Delft Tech
nical University; Dr. H. A. Bakels, Secretary of the University who
made necessary arrangements possible and provided the valued assis
tance of members of his staff, Mr. J. Goedbloed and Mr. C.H. Hoog
straaten; Mr. C. A. Chorus, Head of the Congress Bureau of the Min
istry of Education and Sciences; and spontaneous secretarial ser
vices from our Mrs. M. Barney, J. Howard, A. Willis and F. Harvey.
v
vi Preface
Most of all, again as for the earlier Institute on Optical
Properties of Solids, our heartfelt thanks go to NATO for their
generous suppo!'t of the Infrared Institute leading to this book.
Without the help of Dr H. Arnth-Jensen, Head of the NATO Pure
Science Bureau, the Institute could not have taken place. To
F. Bentley for his interest, encouragement and solution of diffi
cult administrative problems. Thanks are also due to the U.S. Air
Force through,the University of Cincinnati for additional support.
S. S. Mitra and S. Nudelman
April 1970 University of Rhode Island
CONTENTS
1. A Complete system for Interferometric Fourier
Spectroscopy in the Far Infrared • • • • 1
by R. C. Milward
2. Interferometric Spectroscopy 35
by H. A. Gebbie
3. Far Infrared Properties of Atmospheric Gases 38
by R. Zirkind
4. Far Infrared Sources 51
by L. Genzel
5. Far Infrared Detectors 103
by P. L. Richards
6. Developments in Detection and Microsampling
Techniques for Laser Raman Spectroscopy • • 121
by D. O. Landon
7. A Graphical Survey of Free Carrier Magnetooptical
Effects in Semiconductors . • • • • • • • • • • • 134
by E. D. Palik and B. W. Henvis
8. Far Infrared Absorption in Ordered Magnetic Systems •• 19;6
by, M. Tinkham
9. Far Infrared Absorption in Superconductors 223
by M. Tinkham
10. Far Infrared Dispersion and the Raman Spectra of
Ferroelectric Crystals • • • • 247
by A. S. Barker, Jr.
11. Modification of Lattice Vibrations by Impurities 297
by C. W. McCombie
vii
viii Contents
12. Lattice Vibrations of Solid Solutions • 360
by J. van der Elsken, R. Metselaar, and
R. K. Eijnthoven
13. Characteristic Energy Absorption Spectra of Solids 387
by J. N. Plendl
14. High .Pressure Research in the Far Infrared Spectral
Region . . . . . . . . . . . . . • . . . . 451
by J. R. Ferraro
15. Recent Progress on the Low Frequency Spectra of
Coordination Compounds •• • • • • • • • • • • 475
by J. R. Ferraro
16. Low Frequency Vibrations of Polymers 497
by G. Zerbi
17. Electronic Raman Spectra of Trivalent Lathanides 516
by J. A. Koningstein
18. Far Infrared Electronic Transitions in Rare
Earth Ions ........... . . . . . 535
by. A. Hadni
19. Lattice Absorption in the Very Far Infrared • • • • •. 561
by A. Hadni
A COMPLETE SYSTEM FOR INTERFEROMETRIC FOURIER SPECTROSCOPY IN THE
FAR-INFRARED
R. C. Milward+
Research & Industrial Instruments Company
Worsley Bridge Road, London SE26. England
ABSTRACT
The properties and theory of the Fourier transform technique
as applied to far-infrared spectroscopy, have been briefly re
viewed. The main features of a small modular Fourier spectro
photometer system comprised of a Michelson interferometer for the
wavenumber region 10 - 500 cm-l and a Lamellar Grating Interfero
meter for the 3 - 80 cm-l region are described.
Attention has been paid to the operating techniques which are
necessary to obtain optimum performance, and the typical applica
tions for which these instruments are used. A number of absorption
and reflection spectra (transformed by digital computation or by a
special analogue computer) are displayed, to demonstrate the wide
range ~nd high resolution capability (0.1 cm-l) of these instru
ments when used with Golay infrared detectors.
INTRODUCTION
Recent discoveries of a wide range of physical and chemical
phenomena occuring in the low wavenumber or far-infrared region of
the electromagnetic spectrum, 5 cm-l to 500 cm-l (wavelengths of
2,000 microns to 20 microns), have led to a growing demand for im
proved instrumentation for optical spectroscopy in this spectral
region, which until the last decade had received little attention
due to the serious experimental difficulties created by the lack
of intense broad band radiant sources and sufficiently sensitive
detectors for this characteristically low energy radiation. While
+ Present address: Societe Coderg, y2 Clichy, France
2 R. C. Milward
moderately powerful "monochromatic" sources of radiation for the 1
millimetre and sub-millimetre region have been recently developed ,
mainly using microwave techniques, they have not yet been fully
utilized for continuous broad band spectroscopy.
The de~nd for improved instrumentation has been best realized
in the form of interferometric Fourier spectrometers2, which under
these adverse conditions have yielded superior performancesto
those of conventional grating spectrometers3, owing to their abil
ity to record all parts of the spectrum of interest simultaneously
and achieve high resolving powers using relatively large source
apertures. These factors enable the otherwise low detector signal/
noise ratios to be boosted to a level which allows good quality
far-infrared spectra to be recorded in a fast and routine manner
and permits higher limiting resolutions (- 0.1 cm-l) to be
achieved in practice. Another useful property of Fourier spec'tro
photometers is that they allow wide ranges of the far-infrared
spectrum to be recorded in a single scan, a.t constant resolution,
and with none of the problems of "false energy" usually associated
with conventional infrared grating spectrometers. The principle
disadv:antage of the interferometric method is, that as the spec
trum of\ interest is not immediately displayed but has to be derived
from Fourier analysis of an interference pattern ('interferogram'),
con#4erable delays may be incurred in obtaining the spectrum un
less' ade~uate facilities are· readily accessible in the form of
high-speE\d digital computers or the special purpose analogue com
puters which are now available.
Two types of interferometric modulator have been employed for
Fourier spectroscopy in the far-infrared, the Michelson interfero
meter4, and the Strong and Vanasse-type lamellar grating interfero
meter5• The Michelson interferometer has been the most commonly
used instrument as it is of relatively simple construction and has
been found to give a good performance over the far-infrared spec
tral region 10 - 500 cm-l when stretched "Melinex" (polyethylene
tereEhthalate) films of suitable thickness are used as beam split
ters. It is not, however, particularly well suited for use at
very low wavenumbers « 20 cm- ), where radiant energy from conven
tional sources is very weak, as the Michelson configuration allows
only half of the total energy available to be utilized and further
more, multiple interference effects occurring within the thin beam
splitter films themselves, bring about an unwanted total modulation
of the interferometer transmission function. The variable groove
depth lamellar grating interferometer, which acts as a divider of
wave front, has received less attention due to its more difficult
construction, but has been found to give a better performance7
than the Michelson interferometer at wavenumbers < 30 cm-l, due to
the fact that- the lamellar grating facets act as perfect reflec
tors for the very far-infrared and that the design allows all of