The selective preparation of excited vibrational states using the stimulated resonance Raman effect

A nonperturbative treatment of stimulated resonance Raman (SRR) pumping is developed. This theory is based upon the derivation of an effective Hamiltonian for the interaction of the electric field with the molecular electronic-vibrational-rotational states. The resulting reduction in the number of coupled differential equations describing the SRR effect allows for a convenient numerical solution, which is important in intense laser fields. In addition, when the spectral transitions are resonant or sufficiently power broadened, the solutions become analytic. An application of the theory to the I₂ system shows the possibility of selectively populating high vibrational levels (ν′ ≥ 10) in the ground electronic state. Most importantly, it is possible to selectively populate all the vibrational levels by suitable variations in the frequencies and proper selection of the intensities and durations of the applied laser fields.