Xu S J, Xiong Shi-Jie, Shi S L
Department of Physics and HKU-CAS Joint Laboratory on New Materials, The University of Hong Kong, Hong Kong, China.
J Chem Phys. 2005 Dec 8;123(22):221105. doi: 10.1063/1.2140701.
We report on a photoluminescence observation of robust excitonic polarons due to resonant coupling of exciton and longitudinal optical (LO) phonon as well as Fano-type interference in high quality ZnO crystal. At low enough temperatures, resonant coupling of excitons and LO phonons leads to not only traditional Stokes lines (SLs) but also up to second-order anti-Stokes lines (ASLs) besides the zero-phonon line (ZPL). The SLs and ASLs are found to be not mirror symmetric with respect to the ZPL, strongly suggesting that they are from different coupling states of exciton and phonons. Besides these spectral features showing the quasiparticle properties of exciton-phonon coupling system, the first-order SL is found to exhibit characteristic Fano lineshape, caused by quantum interference between the LO components of excitonic polarons and the continuous phonon bath. These findings lead to a new insight into fundamental effects of exciton-phonon interactions.
我们报道了在高质量ZnO晶体中，由于激子与纵向光学（LO）声子的共振耦合以及法诺型干涉而产生的强激子极化子的光致发光观测结果。在足够低的温度下，激子与LO声子的共振耦合不仅导致了传统的斯托克斯线（SLs），除了零声子线（ZPL）之外，还产生了高达二阶的反斯托克斯线（ASLs）。发现SLs和ASLs相对于ZPL不是镜像对称的，这强烈表明它们来自激子和声子的不同耦合状态。除了这些显示激子-声子耦合系统准粒子特性的光谱特征外，还发现一阶SL呈现出特征性的法诺线形，这是由激子极化子的LO分量与连续声子库之间的量子干涉引起的。这些发现为激子-声子相互作用的基本效应带来了新的见解。
