采用圆偏振啁啾飞秒激光脉冲操控CS_2分子的相干拉曼散射过程

Manipulation of coherent Raman scattering process in CS_2 by using chirpped circularly polarized femtosecond pulses

采用两束圆偏振啁啾飞秒激光脉冲,非共线相干激发三原子分子CS2液体.在相位匹配的方向上,探测到由CS2频率为397cm-1的振动模式产生的强度对称分布的相干反斯托克斯拉曼散射(CARS)信号和相干斯托克斯拉曼散射(CSRS)信号.当调整两束激发光的圆偏振状态时,CARS,CSRS信号的强度、偏振、波长均发生规律性的改变:CARS,CSRS信号的强度分布反映了CS2在不同极化状态下的受激拉曼散射截面大小;信号光的偏振方向决定于角动量守恒定律;信号波长的移动体现了CS2不同振转能级之间的跃迁.上述信息对了解CS2分子和其分子的CARS和CSRS效应的机理和行为是有参考意义的.

The coherent anti-Stokes Raman scattering （CARS） and coherent Stokes Raman scattering （CSRS） signals of vibration mode at 397cm-~ of CS2 liquid are manipulated by using two chirped circularly polarized femtosecond pulses in non-collinear excitation geometry. Along the phase matching direction intensity distributions, polarizations and wavelengths of CARS and CSRS signals vary regularly as the polarizations of the laser beams are changed. The intensity distributions of CARS and CSRS reflect the scattering cross sections of the stimulated raman scattering of the sample under different circularly polarizations. The polarizations of CARS and CSRS follow the conservation law of the angular momentum of the excitations. The frequency shifts of CARS and CSRS demonstrate the transitions between the rotational energy levels of CS2. The above information is helpful for understanding the mechanism and the behaviors of the CARS and CSRS of CS2 as well as other molecules.