Molecular dynamics in low vibrational states investigated by fs time-resolved coherent anti-Stokes Raman spectroscopy technique

摘要

The molecular dynamics process is investigated in this paper using a broadband fs time-resolved coherent anti-Stokes Raman spectroscopy (CARS) technique. By varying the timing of laser pulses, low vibrational 163states are started and studied on both the electronically excited B(~(3)(PI)_(0u)~(+)) state and ground X(~(1)(SIGMA)_(0g)~(+)) state of iodine in the gas phase at room temperature. According to change the pump wavelength or Stokes pulse as well as the wavelength of the detection window for the CARS signal, dynamics on different potential-energy surfaces can be accessed and detected by the CARS spectroscopy. Results show that the period of the oscillation is decreased for the excited B(~(3)(PI)_(0u)~(+)) state as the wavelength of the pump pulses is increased, while it is increased for the ground X(~(1)(SIGMA)_(0g)~(+)) state with the increase of the Stokes wavelength.