Trial Experiment of Mass Analyzed Threshold Ionization Spectroscopy : Application for High Sensitive and Selective Detection of Transition Metal Compounds with Week Bonds

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In this research, I have aimed at developing an apparatus of"Mass Analyzed Threshold Ionization Spectroscopy" that can be applied for direct and selective detection of compounds with relatively week chemical bonds in order to understand reaction mechanism involving transition metal centers. This year, following the last year works (mainly design and construction of the apparatus), I have advanced the improvement of the existing apparatus of "VUV Single Photon Ionization-TOF mass spectroscopy". By using this device, some TOF-MASS spectra and the ionization wavelength dependence of ion species population formed through ionization by single-photon in the neighborhood of ionization threshold of aromatic compounds or transition metal carbonyls. I have groped for a possibility of "mass-selective threshold spectroscopy" all through remodeling the existing apparatus and these experimentsIn my experimental system, a wide wavelength range (120 - 180 nm) line tunable VUV coherent light (line widt … More h - 0.4 cm^<-1>) was generated by means of two-photon resonance four-wave difference frequency mixing with Kr gas as non-linear medium. In order to separate the intense input first-order lights and the generated VUV light, a VUV monochromator was introduced between the Kr vessel for VUV generation and the ionization region. By this improvement, the possibility of the multiphoton ionization or the secondary photolysis of ionic species by intense first order input laser light could be excluded from the experimental data. It was observed that there was the photolysis wavelength dependence of the ionic species distribution in the neighborhood of ionization threshold in the case of homogenate benzene. Furthermore, an ion signal reliability was improved through the correction of the intensity fluctuation of ionization VUV light by a two-channel boxcar averager (SRSSR235/250x2/235/275) with the analog operation treatment, which was purchased by this Grant-in-Aid for Scientific Research (C). By this improvement, it has been possible to see some structures in the action spectra (ionization wavelength dependence) of the formation of ionic species distribution in the neighborhood of ionization threshold region. The reproducibility of these structures have been examined and also discussed theoretically. Moreover, the existing apparatus was adapted for "mass-selective threshold spectroscopy" mainly in the pulse molecule jet part. The experimental conditions, which will be suitable to this spectroscopy, have been examined together with further improvements of the existing apparatus though any meaningful data have never been observed in this threshold spectroscopy. Less