This book is concerned with recent experimental and theoretical work
dealing with phenomena created by the transient dipoles and
polarizabilities produced by intermolecular interactions. The for- mer
produce absorption from the microwave to the optical regions of the
spectrum and the latter produce Rayleigh and Raman scattering; such
absorption and scattering would be absent without collisions. Static
properties, such as dielectric constant, refractive index, and Kerr
effect, also exhibit the effects of induced dipoles and
polarizabilities. The first observation of an infrared absorption
spectrum pro- duced by the collisions of molecules which ordinarily do
not have an allowed dipole transition was reported in 1949 (Crawford,
Welsh, and Locke). The first observation of depolarized Rayleigh spectra
due to collisions in atomic gases appeared in 1968 (McTague and
Birnbaum). However, it was not until 1977 that the first conference
dealing with collision-induced phenomena was organized by J. D. Poll at
the University of Guelph. This conference was mainly concerned with
studies of collision-induced absorption in gases. Light scat- tering
received more attention at the second meeting of the colli- sion-induced
community in 1978, at the E. Fermi Summer School on "Intermolecular
Spectroscopy and Dynamical Properties of Dense Sys- tems," organized by
J. Van Kranendonk. However, the emphasis was still on collision-induced
absorption in compressed gases, although some work on liquids, solid H,
and related subjects such as ro- 2 tational relaxation was included. The
third induced phenomena con- ference, organized by F.