Stimulated resonant Raman scattering of light in anthracene crystals

The investigation of stimulated resonant Raman scattering of light (SRRS) is carried out on thin plane‐parallel anthracene crystals ( d = 2 to 45 μm) at low temperatures ( T = 1.5 to 40 K). The resonance excitation at the bottom of the lowest exciton band is produced by a pulsed tunable dye laser. It is shown that under resonance excitation at optical pumping levels P ≈︁ 3 MW/cm 2 up to nine SRRS Stokes components of intramolecular vibrations 395, 1167, and 1402 cm −1 , are observed, the three Stokes components of 1402 cm −1 vibrations being the most intensive ones. Characteristic dependences of the intensity of SRRS Stokes components on pumping level and crystal tempe ature for different exciting frequencies are obtained. An anomalous intensity increase of the 49 cm −1 RS Stokes component is found attributed to RS on nonequilibrium phonons of the lowest optical branch. The results of the measurements are compared with the data on spontaneous resonant RS of light in anthracene crystals.