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Theoretical analysis of correlation between ionization threshold fluence in IR-MALDI and IR absorption spectrum of matrix molecules

Authors

  • Makoto Hatakeyama,

    1. Department of Biomolecular Engineering, Tokyo Institute of Technology, B-70, 4259 Nagatsuta, Midori-ku, Yokohama, Japan
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  • Takako Mashiko,

    1. Quantum Chemistry Division, Graduate School of Science, Yokohama-city University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan
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  • Hisanao Hazama,

    1. Medical Beam Physics Laboratory, Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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  • Kunio Awazu,

    1. Medical Beam Physics Laboratory, Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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  • Masanori Tachikawa

    Corresponding author
    1. Quantum Chemistry Division, Graduate School of Science, Yokohama-city University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan
    • Quantum Chemistry Division, Graduate School of Science, Yokohama-city University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan
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  • These authors contributed equally to this work.

Abstract

To investigate the correlation between the wavelength dependence of ionization threshold fluence of target molecule in matrix-assisted laser desorption/ionization by infrared (IR) laser and the IR absorption spectrum of matrix molecule, we have analyzed the IR absorption spectra of four matrix molecules using density functional theory and correlated ab initio molecular orbital method. The calculated IR absorption spectra of the isolated molecules showed more qualitative correlation with the wavelength dependence of ionization threshold fluence than those of the solid state structures. We can consider that a portion of matrix molecules lost the ordered crystal structure and that the transition to the diluted or isolated state occurred at the early process of IR laser irradiation. © 2012 Wiley Periodicals, Inc.

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