Observation of Excited υ_s(NO₂) and Relaxation Process of HNS in Solution by CARS Technique

Investigation on vibrational excitation and relaxation process will provide important in-formation for a better understanding of ultrafast dynamic response of energetic materials. Using sub-ps time-resolved coherent anti-Stokes Raman scattering (CARS) experiments, we directly observe excitation of vibrational mode ν_s(NO₂) and its relaxation process of ground state HNS (2,2',4,4',6,6'-hexanitrostillbenein) in solution. The results show that ν_s(NO₂) at 1385 cm^-1 has been excited and relaxation time of 0.38 and 8.5 ps is obtained. The possible quantum beat frequencies are also discussed via fs-CARS experiments. The original results provide an insight into ultrafast process of energetic materials.