斯托克斯和反斯托克斯拉曼位移差与时间反演对称性

Difference Between Stokes and Anti-Stokes Raman Shiftsand Time-reversal Symmetry

首先列出若干Stokes和anti-Stokes位移不对称的事例,并在此基础上指出,如果将anti-Stokes散射严格定义为Stokes散射的时间反演行为,则对于初态或末态具有Kramers简并的体系,Stokes和anti-Stokes散射的拉曼位移可以不同.这是因为时间的正过程和反演过程各对应于不同的跃迁途径,其位移大小的差别与简并能级的分裂值相关.

The anti-Stokes scattering was defined as the corresponding time-reversed process of the Stokes scattering. Based on the time-reversal symmetry the differences between one Stokes and its corresponding anti- Stokes Raman shifts have been theoretically demonstrated for the systems with Kramers-degenerate ground or final states. In the former cases the Stokes and its corresponding anti-Stokes Raman lines should display on the same side of the excited line. In the latter cases, they show major differences on two sides of the excited line. However, the whole normal Stokes Raman spectrum of a system may be still symmetric to the whole anti-Stokes spectrum, except in the cases of resonant, or laser, or circularly polarized excitation Raman scattering. This is a preliminary theoretical predication which needs more experimental and theoretical investigations.