Investigation of elastic and depolarizing collisions in strontium using broadband stimulated photon echoes
M. Saïdi, J. Keller, J.-L. Le Gouët
Elastic and depolarizing collisions between excited strontium (5s 5p 3P1) and noble gases are investigated in a broadband stimulated photon echo (SPE) experiment. The stimulated photon echo signal produced under broadband (incoherent) excitation is calculated in the weak field regime both for correlated and for uncorrelated pulses using a simple statistical model for the light field. The relaxation of the echo signal due to elastic collisions is considered and the complete development of the corresponding propagator is derived. The collisional velocity changes concerning the total population and the alignment are compared precisely in the SPE experiment and the corresponding relaxation rates are measured. A simple long-range Van der Waals potential accounts for population scattering data ; total elastic scattering cross sections are deduced from the comparison of experiment and calculation (σelAr = 583(27) Å2; σ elHe = 190(6) Å2). The collisional model is extended for light perturbers to include both the small angle classical scattering region and the diffractive scattering region. Total rates for destruction of alignment are measured in an auxiliary photon echo experiment (σ (2)He = 91 (4) Å2; ; σ(2) Ne = 102 (14) A2 ; σ(2)Ar = 267 (13 ) Å2 ; σ(2)Kr = 329 (21) Å2 ; σ(2)Xc = 370 (13) Å2). SPE data for depolarization are compared with a calculation based upon a long-range anisotropic model potential.
Journal de physique•Jan 1, 1988•7 citations