Li J J, Chen J, Reis D A, Fahy S, Merlin R
Department of Physics, University of Michigan, Ann Arbor, MI 48109-1040, USA.
Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
Phys Rev Lett. 2013 Jan 25;110(4):047401. doi: 10.1103/PhysRevLett.110.047401. Epub 2013 Jan 24.
Illumination with laser sources leads to the creation of excited electronic states of particular symmetries, which can drive isosymmetric vibrations. Here, we use a combination of ultrafast stimulated and cw spontaneous Raman scattering to determine the lifetime of A(1g) and E(g) electronic coherences in Bi and Sb. Our results both shed new light on the mechanisms of coherent phonon generation and represent a novel way to probe extremely fast electron decoherence rates. The E(g) state, resulting from an unequal distribution of carriers in three equivalent band regions, is extremely short lived. Consistent with theory, the lifetime of its associated driving force reaches values as small as 2 (6) fs for Bi (Sb) at 300 K.
激光源照射会导致产生具有特定对称性的激发电子态，这些激发态可驱动等对称振动。在此，我们结合超快受激拉曼散射和连续自发拉曼散射来测定铋（Bi）和锑（Sb）中A(1g)和E(g)电子相干的寿命。我们的结果既为相干声子产生的机制提供了新的见解，也代表了一种探测极快电子退相干速率的新方法。E(g)态是由三个等效能带区域中载流子的不均匀分布产生的，其寿命极短。与理论一致，在300 K时，铋（Bi）（锑（Sb））中其相关驱动力的寿命小至2（6）飞秒。
