Density evolution of the picosecond time-domain CARS responses from carbon dioxide gasстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Results of a joint experimental and theoretical study of CARS transients produced by picosecond two-color pumping of the CO2 Q-branch at 1285 cm(-1) are reported. The coherence decay patterns recorded in a wide dynamic range (3-8 decades) and in a broad gas density interval (rho = 0.02-20 amagat) made it possible to track different channels of collision-induced relaxation. The undertaken signal simulations account for the finite pump-probe pulse durations and also for the collision-perturbed Doppler effect, vibrational dephasing and collisional mixing of rotational states. The last effect was tackled by applying the quantum fast-collision model of rotational relaxation. Our recent data on the other Fermi-dyad component at 1388 cm(-1) were also simulated in the same way to derive a set of optimized relaxation rate parameters. New features revealed at low densities are ascribed to interference between the velocity and rotational relaxation channels