Dicke effect in hydrogen S0(0) rotational transition observed by time‐domain CARS

Abstract

AbstractThe Dicke effect in the hydrogen S0(0) rotational transition (354 cm−1) in forward scattering geometry was observed using time‐domain CARS. Dicke effect measurements were performed at room temperature and with cooling by liquid nitrogen. The observed slowest decays of the impulse responses correspond to the narrowest S0(0) transition spectral linewidths of 1.1 × 10−3 cm−1 (296 K) and 0.45 × 10−3 cm−1 (85 K). At 85 K, the impulse responses coincided satisfactorily with the theoretical values calculated for statistically independent collisional perturbations of translational and rotational motions. At 296 K, some discrepancy between experiment and theory was observed. Copyright © 2002 John Wiley & Sons, Ltd.