Surveys the developments in Brillouin scattering during the past fifteen years. Mainly classical effects are described, therefore excluding stimulated and resonance Brillouin scattering. The study is limited so that the frequency interval of the acoustic excitations lies in the hypersonic regime.

https://iopscience.iop.org/article/10.1088/0034-4885/45/3/002/pdf

Brillouin scattering in condensed matter

A new design of a plane mirror Fabry-Perot interferometer with the mirror blanks freely supported by horizontal rings is described. Special attention is paid to the surface flatness and dielectric coatings of the mirrors. It is shown that any two piezoelectrically scanned Fabry-Perot interferometers can be synchronized in tandem operation using simple optics and standard electronic driving and stabilization equipment. Applications of the tandem system to Brillouin scattering are given. The observation of Brillouin spectra of supported thin plastic films and of a clamped metal surface is reported.

Tandem multipass Fabry-Perot interferometer for Brillouin scattering.

Interferometric techniques have been applied in a high resolution study of the polarized Raman components (Q branches) corresponding to the totally symmetric vibrational modes of CO, CH4, and CF4 in the liquid phase. Additional unpublished data for N2 and O2, as well as limited results of dilution studies in liquid argon, are reported. Emphasis is placed upon the measurement of variations in frequency shift and spectral width along the liquid–vapor coexistence line from the triple point to within 0.2 K of the critical point for each pure liquid. The character of the observed linewidth variations exhibits distinct differences from liquid to liquid, especially in the neighborhood of the triple and critical points. A consistent interpretation of the results suggests that a substantial contribution to the N2 and O2 linewidths is associated with the effect of intramolecular vibration–rotation coupling. The CH4 data support the predictions of Hills and Madden (i) that the long wavelength, hydrodynamic, density ...

Pure vibrational Raman spectra of simple liquids: O2, N2, CO, CH4, CF4

Evidence for structural transformations in polymer melts

Brillouin light scattering (BLS) is now established as a powerful tool for the investigation of spin waves in layered magnetic structures. Due to the strong magneto-optical interaction in the majority of magnetic metals BLS allows the examination of spin waves in films with extremely small thicknesses down to 1-2 monolayers. This gives us the opportunity to obtain important information about magnetic properties of such two-dimensional systems. Applied to magnetic bilayers and multilayers, BLS makes it possible to elucidate collective excitations in these complex structures as well as to analyse mechanisms of the interlayer coupling. The restricted geometry of layered systems considerably influences the interaction of spin waves with light resulting in many peculiar features of the light-scattering phenomenon.

http://iopscience.iop.org/article/10.1088/0953-8984/6/36/002/pdf

Light scattering from spin waves in thin films and layered systems

A data acquisition system for high-resolution Fabry-Perot interferometry is described. Used in conjunction with a piezoelectrically scanned Fabry-Perot, this apparatus compensates for all frequency drifts, maintains interferometer alignment, and allows extended data acquisition times in selected regions of a spectrum.

W. May

Papers

Automated data acquisition and stabilization system for Fabry-Perot interferometry.