Ultrafast motion of liquids C₂H₄Cl₂ and C₂H₄Br₂ studied with a femtosecond laser

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• 作者：Jaw-Luen Tang ; Chen-Wei Chen ; Jiunn-Yuan Lin ; Ying-Dar Lin ; Chia-Chen Hsu ; Tai-Huei Wei and Tzer-Hsiang Huang
• 关键词：Vibrational spectroscopy ; Femtosecond laser ; Raman-induced optical Kerr effect ; 1 ; 2-dihaloethane liquids
• 刊名：Optics Communications
• 出版年：2006
• 期刊代码：50_00304018
• 类别：ph
• 出版时间：15 October 2006
• 卷：266
• 期：2
• 页码：669-675
• 文件大小：272 K

摘要

Transient optical Kerr effect of liquids C₂H₄Cl₂ and C₂H₄Br₂ is investigated, for the first time to our knowledge, with a femtosecond (fs) probe laser delayed with respect to a coherent fs pump laser. Coherent coupling and electronic Kerr signals are observed around zero delay when pump and probe overlap. Persisting after the pump-probe overlap are Kerr signals arising from the torsional and other intramolecular vibrations of the trans and gauche conformations; Kerr signals arising from the intermolecular motion are also observed. Vibrational quantum interference is only observed in liquid C₂H₄Br₂ and the related beats data are fitted with the torsional vibrations, 91 cm⁻¹ (gauche) and 132 cm⁻¹ (trans), and the CCBr angle-bending vibrations, 231 cm⁻¹ (gauche) and 190 cm⁻¹ (trans), with dephasing times, 0.45 ps, 0.45 ps, 2 ps, and 1.5 ps, respectively. These vibrational frequencies agree with those obtained in the frequency-domain. That no vibrational mode is observed for C₂H₄Cl₂ might be attributed to ineffective Raman-pumping. Kerr signals observed after the pump-probe overlap are Fourier transformed to give the spectra of the intermolecular motion and the vibrational spectrum, which agrees with the one observed in the infrared absorption and/or Raman scattering heretofore.