Instantaneous vibrational frequencies of diffusing and desorbing adsorbates: CO/Pt(111).

• Inoue, Ken-ichi

• Watanabe, Kazuya

• 松本, 吉泰

抄録

Electronic excitation of metal by intense laser pulses stimulates nuclear motions of adsorbates through nonadiabatic coupling, resulting in diffusion and desorption of adsorbates. These processes take place via precursor states: adsorbates whose vibrational modes with respect to substrate are highly excited. This paper reports the dynamics of precursor states of CO on Pt(111) probed by use of infrared-visible sum frequency generation with phase-sensitive detection, which allows us to obtain the second-order nonlinear susceptibility and thus the vibrational response function. Without pump pulses at 400 nm, the inverse Fourier transformation of the vibrational response function reveals a free induction decay of vibrational polarization of C-O stretching created by a short infrared pulse. The free induction decay is perturbed when an intense 400-nm pump pulse following the infrared pulse is irradiated, because diffusion and desorption of CO are induced by the pump pulse. The time evolution of instantaneous C-O stretching frequency retrieved from the perturbed free induction decay shows a redshift followed by a rapid reverse shift when the fluence of pump pulse is high enough to desorb CO. This indicates that the frustrated modes of CO is first substantially excited and then the parallel momentum of CO is converted to the normal one through mutual collisions, leading to substantial excitation of the external stretching mode of CO.

収録刊行物

• The Journal of chemical physics

  The Journal of chemical physics 137 (2), 2012-07

  American Institute of Physics

キーワード

• adsorbed layers
• adsorption
• carbon compounds
• desorption
• diffusion
• Fourier transforms
• high-speed optical techniques
• nonlinear optical susceptibility
• optical frequency conversion
• platinum
• red shift
• vibrational modes

詳細情報

• CRID: 1050845760667520000
• NII論文ID: 120004770241
• NII書誌ID: AA00694991
• ISSN: 00219606
• HANDLE: 2433/159717
• 本文言語コード: en
• 資料種別: journal article
• データソース種別:
  • IRDB
  • CiNii Articles