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Updated: Jul 2, 2026

Direct Imaging of Laser-driven Ultrafast Molecular Rotation
Published on: February 4, 2017
Excited-state molecular vibration observed for a probe pulse preceding the pump pulse by real-time optical
Takayoshi Kobayashi1, Juan Du, Wei Feng
1Department of Applied Physics and Chemistry and Institute for Laser Science, the University of Electro-communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan. kobayashi@ils.uec.ac.jp
Abstract:
It is shown experimentally that the absorbance change observed in the "negative" time range, where probe pulse precedes pump pulse in real-time vibrational spectroscopy is induced only by the excited-state wave-packet motion as theoretically expected. Coherent molecular vibration of a polymer in the excited state was observed in the real-time trace without the effect of wave-packet motion in the ground state, which usually makes it difficult to ascribe the signal either to the ground state or to the excited state.
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