Vibronic sidebands of coherent phonon states

2019-07-24 07:44:54

modes states phonon coherent lineshape

责任者: Heber, J.;Pukhov, K.K. 单位: Institute of Solid State Physics, Darmstadt University of Technology, D-64289 Darmstadt, Germany 来源出处: Radiation Effects and Defects in Solids,2003,158(1-6):257-262 摘要: Recently experiments have been reported about phonon sidebands in doped crystals, which may originate from coherent phonon states. The corresponding modes are either confined phonon modes in nanocrystals or localized phonon modes in bulk materials, both showing small damping due to phonon-phonon interaction. We present a theory of the lineshape of vibronic sideband spectra due to coherent phonon states using the conventional model of linear electron-phonon coupling and displaced equilibrium positions of the oscillators in the initial and final electronic states. Unlike in the conventional theory, the initial state of the oscillator is taken as a coherent phonon state and not as a thermalized one. Under these conditions we got an exact analytical solution for the lineshape of the vibronic sideband. The lineshape is determined by two parameters, the Huang-Rhys parameter S and the coherence parameter a of the phonon state. For α = 0 the lineshape converts into the standard Pekarian form for T = 0. 关键词: Phonons;Coherent light;Lattice vibrations;Oscillators (electronic);Damping;Nanostructured materials;Crystal structure;Coherent phonon states;Vibronic spectra;Lineshape;Phonon modes