Femtosecond reflectivity study of coherent phonons in doubly photoexcited bismuth |
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Authors: | Taeho Shin |
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Institution: | 1. Department of Chemistry, Chonbuk National University, Jeonju 54896, Republic of Korea;2. Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139-4307, USA |
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Abstract: | Ultrafast optical excitation generates coherent A1g optical phonons in bismuth via the mechanism of displacive excitation of coherent phonons (DECP). Here, femtosecond pump-probe reflectivity spectroscopy examines the dynamics of coherent phonons in doubly photoexcited bismuth. Two successive pump pulses are employed to generate optic phonons and thus to investigate the phonon dynamics including bond softening and dephasing with variable pump fluence and inter-pump separation times. Combined with thermal analysis, it distinguishes thermal and nonthermal effects of photoexcitation on the phonon dynamics. It also reveals that photocarriers relax via electron-hole recombination and diffusion out of the optical penetration depth on ultrafast timescales of 10–20?ps. |
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Keywords: | Femtosecond Spectroscopy Bismuth Phonons |
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