|場所||創成科学研究棟 4F 会議室|
|講演者||李 遠鵬 先生 (National Chiao Tung University)(台湾国立交通大学 教授)|
|タイトル||Studying Reaction Intermediates using Time-resolved Fourier-transform Infrared Spectroscopy and p-H2 Matrix Isolation Technique|
Either one or both of two techniques employed in our laboratory for studying transient species in chemical reactions will be introduced.
We developed the time-resolved Fourier-transform infrared (TR-FTIR) absorption spectroscopy to investigate IR absorption of gaseous transient species. A flow reactor with a multipassing UV photolysis beam and a multipassing IR probe beam is coupled to a step-scan FTIR spectrometer with both dc- and ac-detection to record temporal profiles of the infrared absorption of reaction intermediates. IR absorption spectra of several reactive species such as CH3OO,1 CH3SO, CH3SO2,2 ClCOOH,3 and CH3C(O)OO were recorded. Spectral assignments were made based on reaction mechanisms and comparison of observed vibrational wavenumbers and rotational contours with those predicted quantum-chemically. Related reaction kinetics will also be discussed. In this talk, the identifications of ClCOOH and CH3C(O)OO will be discussed.
Para-hydrogen (p-H2) has recently emerged as a new matrix host. Because of the ‘softness’ associated with the extensive delocalization of the H2 moieties, new characteristics of molecules isolated in this quantum solid are explored. We demonstrated that the internal rotation of methanol persists in solid p-H2 by observation of splittings of the E/A torsional doublets in internal-rotation-coupled vibrational modes.4 We also provided direct spectral evidence that CH3F isolated in p-H2 rotates about only its symmetry axis, and not about the other two axes by observation of two weak absorption lines from the E (K = 1) level and one intense feature from A (K = 0) for degenerate modes ν4−ν6 of CH3F.5 We demonstrated another feature of solid p-H2, the absence of cage effect, by reaction of Cl, produced from in situ photodissociation of Cl2, with HCOOH; complexes of Cl with HCOOH were observed. This feature might open up a new direction for investigating the entrance channel of bimolecular reactions and their mode selectivity by carrying out reactions without kinetic energy.
|連絡先||光電子物性研究分野 太田 信廣 (内線 9410)|