Molecular nitrogen at 0.8 atm and 300 and 500 K and methane at 0.8 atm and 300 K were subjected to optical lattices formed by narrow-band 532-nm laser pulses with intensities on the optical axis near, but below, the gas ionization limit. A third pulse was introduced to experimentally probe the response, as a function of the lattice velocity, of the gas to the deep monochromatic potential wells formed by the lasers. Coherent Rayleigh-Brillouin scattering (CRBS) line shapes were recorded and compared to numerically predicted magnitudes of the density perturbations induced in the gas. Both experimental results and those from direct simulation Monte Carlo simulations show a deviation from previously published low-intensity CRBS line-shape models. The deviation indicates a trend, as a function of lattice velocity, similar to that relating to previously published energy and momentum transfer calculations for high-intensity lattices. Furthermore, the deviation indicates a maximum intensity at which current CRBS theory is valid.

• Received 12 January 2013

DOI:https://doi.org/10.1103/PhysRevA.87.033825