Time Behavior of Raman Scattering Under Pulsed Light Excitation

Eiichi Hanamura, T. Takagahara

Competitive behavior of two channels of resonant Raman scattering and luminescence is discussed for the giant two-photon excitation of excitonic molecules in CuCl. The stochastic theory of intermediate state interaction is applied to describe the time-integrated and time-resolved emission spectra of the excitonic molecule excited resonantly by a short light pulse. Particularly as for the time-resolved spectrum, the frequency-time uncertainty due to the finite observation time is incorporated in the present theory. Our theory explains the observed characteristics of the emission spectra, and the relaxation constants of the excitonic molecule and the exciton in the final state are determined from comparison between the observed and calculated spectra.

V. A. Zubov, M. M. Sushchinskiǐ, I. K. Shuvalov

J. Arnold Koningstein

V. A. Morozov, P. P. Shorygin

Abstract The expressions for the pulse shapes of secondary radiation in the frequency range of Rayleigh scattering and resonance fluorescence and in the range of Raman scattering and shifted resonance fluorescence are obtained on the basis of the quantum treatment of transformation of light pulses, the resonance conditions for Raman and Rayleigh scattering being considerably different. The characteristic cases of different pulse shapes of Raman and Rayleigh scattering are considered for the condition when the molecules are irradiated by light pulses which are shorter then the lifetime of the excited state of the molecule and are weak enough not to result in saturation.

Махвиладзе Тариэль Михайлович, Сарычев Михаил Евгеньевич, Leonid A. Shelepin

N. Fabricius, Kurt Nattermann, Dietrich von der Linde

From a classical point of view the generation of Stokes light by stimulated Raman scattering (SRS) is not possible unless a Stokes input signal is supplied. On the other hand, the gain in SRS can be so large that without input the spontaneous build-up of strong Stokes waves can be observed. A proper quantum theoretical description1 shows that this spontaneous initiation of Stokes generation is due to microscopic random fluctuations originating from quantum noise associated with the dynamical variable Q(t) which is active in the Raman process, e.g., a molecular normal mode coordinate. In highly transient SRS -when the duration of the excitation pulse is shorter than the dephasing time- the Stokes field is proportional to the initial Heisenberg operator Q(0) describing the state of the system just before the excitation pulse is turned on (t=0). In this case the statistics of the final Stokes pulse energy is determined by quantum mechanical uncertainties associated with the random Raman polarization of the initial state2. On the other hand, in a steady state situation the Stokes pulse fluctuations are substantially reduced and the Stokes pulse energy is stabilized as a result of damping processes.