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Coherent molecular vibrational dynamics of CH 2 stretching modes in polyethylene studied by femtosecond‐CARS
Author(s) -
Kozai Takanori,
Kayano Yuya,
Aoi Takahito,
Tsurumachi Noriaki,
Nakanishi Shunsuke
Publication year - 2015
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.4663
Subject(s) - dephasing , femtosecond , vibrational energy relaxation , raman spectroscopy , relaxation (psychology) , excited state , molecular vibration , polyethylene , phonon , chemistry , molecular physics , coherent spectroscopy , materials science , atomic physics , coherent anti stokes raman spectroscopy , laser , raman scattering , optics , condensed matter physics , physics , psychology , social psychology , organic chemistry
We have studied the coherent molecular vibrational dynamics of CH 2 stretching modes in polyethylene by time‐resolved femtosecond coherent anti‐Stokes Raman spectroscopy. We observed that the coherent vibrational relaxation of symmetric CH 2 stretching modes in polyethylene at room temperature is much faster than that previously measured in polyvinyl alcohol. In addition, it was detected that, at low temperature, the coherent vibrational relaxation of the symmetric stretching modes evidently becomes slower compared with that at room temperature. These temperature‐dependent measurements enable us to discriminate the contribution of pure dephasing mechanism, due to phonons and two‐level systems in polymer, from the contribution of lifetime of the vibrational excited state to the coherent vibrational relaxation of CH 2 stretching modes. We conclude that the coherent vibrational relaxation of symmetric CH 2 stretching modes at room temperature consists of the contribution of lifetime and approximately 1.5 times larger contribution of pure dephasing. Copyright © 2015 John Wiley & Sons, Ltd.