John A. Bell

Elastic constants of Cu/Nb superlattices

Abstract Brillouin scattering has been performed on Cu/Nb metal superlattices with a multipass tandem interferometer. Behavior similar to that reported by Kueny et al. [Phys. Rev. Lett., 48, 166 (1982)] has been observed for the Rayleigh wave dispersion with bilayer periodicity. Multiple guided acoustic waves have been observed and their dispersion measured in order to obtain the variation in the c44 and c33 elastic constants with bilayer thickness.

Brillouin scattering from Love waves in Cu/Nb metallic superlattices

Love waves have been observed for the first time by Brillouin scattering. The c12 constant of the metallic superlattice Cu/Nb has been measured.

Elastic constants of, and Stonely waves in, molybdenum films measured by Brillouin scattering

The dispersion of Rayleigh, Stonely, and Sezawa acoustic waves guided by deposited thin molybdenum films has been used to evaluate selected elastic constants and film homogeneity. This work includes the first experimental observation of Stonely waves by Brillouin scattering.

Recent Progress In The Measurement Of Temperature And Salinity By Optical Scattering

Recent progress is described in the use of Brillouin and Raman scattering for the measurement of temperature and salinity in the ocean. The use of Brillouin scattering is described for the measurement of the sound velocity, and the use of Raman scattering is described for the independent measurement of the temperature and salinity. Coupling these techniques permits the assessment of both temperature and salinity. The experimental techniques are described together with the results of recent experiments and an assessment of the errors to be expected.

Brillouin scattering studies of the elastic properties of metallic superlattices

Abstract The determination of the elastic properties of metallic superlattices using Brillouin scattering is discussed. Previous work by our group is reviewed and preliminary results for Ag/Pd superlattices are reported.

Brillouin spectroscopy of multilayer films

Abstract The elastic properties of molybdenum films, Cu/Nb and Mo/Ta superlattices and cadmium arachidate Langmuir-Blodgett films have been measured using Brillouin scattering. Specifically the in-plane shear constant of Cu/Nb superllatices was obtained through the first observation of the Love modes by Brillouin scattering. The Rayleigh and Stoneley waves, confined to the air-molybdenum and substrate-molybdenum interfaces respectively, were measured to determine the mechanical homogeneity of a molybdenum film. The elastic constants of Langmuir-Blodgett organic films of cadmium arachidate were also evaluated and an anomalously small shear constant was observed.

Brillouin Spectroscopy of Langmuir-Blodgett Films

Using Brillouin scattering we have been able to measure the Brillouin Spectra of thin cadmium arachidate (CdA) films which were deposited by the Langmuir-Blodgett (L-B) technique onto aluminum film substrates. A 9-pass tandem Fabry-Perot interferometer [1] was used to frequency analyze light scattered by multiple, high frequency, thermally-excited surface acoustic waves guided by the CdA film.

Competing Interactions in Metallic Superlattices

Metallic superlattices provide an excellent system to study in a controlled manner a variety of physical phenomena, including superconductivity, magnetism, and electrical transport properties. As will be discussed in this paper, changes in certain of these properties as a function of superlattice modulation wavelength A are found to be correlated with structural changes and elastic property anomalies. The properties of two particular metallic superlattices, Cu/Nb and Mo/Ta, will be discussed in this paper, as examples of how competing interactions manifest themselves in the physical properties of these superlattices.