Spectrochimica Acta Part B 58 (2003) 1171–1175 0584-8547/03/$ - see front matter  2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0584-8547Ž03.00069-7 Determination of linear and nonlinear elastic parameters from laser experiments with surface acoustic wave pulses  H.A. Schuessler, S.N. Jerebtsov, A.A. Kolomenskii* Department of Physics, Texas A&M University, College Station, TX 77843-4242, USA Received 7 July 2002; accepted 28 January 2003 Abstract Time resolved laser techniques enabled the study of the nonlinear evolution of surface acoustic wave (SAW) pulses of very high-amplitudes with acoustic Mach numbers of approximately 0.01. In such waves even shock fronts can be formed during their propagation. Changes of the shape of intense SAW pulses provide information on the nonlinear acoustic parameters and the nonlinear elastic constants of the material. Measurements in polycrystalline stainless steel have shown that a compression of the nonlinear SAW pulse takes place in this metal material yielding a positive parameter of the local nonlinearity. The changes of the SAW pulse shape were calculated using a nonlinear evolution equation and the nonlinear acoustic parameters were determined by fitting the evolution equation to the experimental data. The attenuation of SAWs was determined by measuring low amplitude pulses. In addition, the velocities of longitudinal and shear waves were obtained by registering the precursors of bulk waves at the surface.  2003 Elsevier Science B.V. All rights reserved. Keywords: Nonlinear surface acoustic waves; Nonlinear evolution equation; Pulse compression; Shock front; Laser photoacoustics 1. Introduction Surface acoustic waves (SAWs) propagate along the surface of a solid and produce strains, decaying exponentially from the surface inward the material. They can exhibit large energy densities due to their confinement into the narrow subsurface region, which is of the order of one wavelength in  This paper was presented at the International Conference on Laser Probing (LAP-2002), held in Leuven, Flanders, Belgium, July 2002, and is published in the Special Issue of Spectrochimica Acta Part B, dedicated to that conference. *Corresponding author. Tel.: q1-979-845-7861; fax: q1- 979-845-2590. E-mail address: a-kolomenski@physics.tamu.edu (A.A. Kolomenskii). depth. When strongly excited, SAWs will drive the medium into the nonlinear elastic regime. There- fore, as an intense SAW propagates the evolution of the wave shape in time allows us to obtain information on nonlinear acoustic parameters, and in this way the higher order nonlinear elastic constants of the material. In the last few years such studies w1–4x have emerged mainly by employing efficient ways to couple the energy of the laser pulse to the surface by optimizing the absorption of pulsed laser radiation and by simul- taneously reducing other effects such as reflection, optical breakdown, and ablation. Other SAW exci- tation mechanisms, such as for instance by piezo- electric transducers or particle beams exist, but do