Asymmetric broadening and blue shift of the stimulated Raman scattering spectrum in water under chirped picosecond laser pulse train excitation

Abstract

For the first time, we have revealed an asymmetric broadening and a 35 cm−1 blue shift (up to 3400 cm−1) of the stimulated Raman scattering OH band in water under chirped picosecond pulse train excitation (pulse duration ∼60 ps with 8 ns interval between pulses) while increasing the train length to 25 pulses. From the observed broadening and shift of the OH band centroid, a lower estimate (≥8 ns) of molecular complexes spectral states relaxation time at room temperature was obtained.