NONRESONANT IONIZATION DETECTED IR SPECTROSCOPY FOR THE VIBRATIONAL STUDY IN A SUPERSONIC JET
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Publisher:Ohio State University
A spectroscopic technique for measurement of IR transition in an isolated molecule has been developed. Briefly, this spectroscopy, nonresonant ionization detected IR spectroscopy (NID-IR), uses a UV laser and a tunable pulsed IR laser. A molecule in a supersonic jet is excited to a vibrationally excited level by the IR laser. The vibrationally excited molecule is detected by nonresonant two-photon ionization by the UV laser. Here, the frequency of the UV laser is adjusted to be less than a half of ionization potential to prevent the two-photon ionization of molecules in zero vibrational level. Therefore, the IR transition can be detected by the enhancement of the ion current. This spectroscopy has been applied to o-, m- and p-fluorophenols in a supersonic jet. Combination vibrations are clearly observed. Difference of OH vibrational frequency of cis- and trans- rotational isomers in fluorophenols will also be discussed.
Author Institution: Waseda University, Ohkubo, Shinjuku-ku, Tokyo 169, JAPAN; Waseda University, Ohkubo, Shinjuku-ku, Tokyo 169, JAPAN; Waseda University, Ohkubo, Shinjuku-ku, Tokyo 169, JAPAN