Infrared spectroscopy of jet-cooled tautomeric dimer of 7-azaindole: a model system for the ground-state double proton transfer reaction.
To investigate the ground-state double proton transfer (GSDPT) reaction, we carried out a laser spectroscopic study on the tautomeric dimer of 7-azaindole in a supersonic jet. We have recorded an infrared (IR) spectrum of the tautomeric dimer in the S(0) state. The NH band exhibits a broad and less-structured pattern. The band pattern is discussed on the basis of the hierarchical vibrational interaction mechanism. As a result, much higher density of state (DOS) at the NH stretch level is expected than that of the normal dimer. Such a high DOS should be related to the anharmonicity of the potential energy surface near the barrier of the GSDPT reaction. To get more information, an N-D deuteration effect is examined. In the present experiment, five deuterated dimers are identified by visible-visible or IR-visible population labeling spectroscopy. The IR band pattern of the NH-ND dimer is very different from that of the NH-NH dimer. Among several N-D deuteration effects, a change in a condition between the inter- or intramolecular vibrational energy flows due to the single N-D deuteration is considered to be important.
Ishikawa
Haruki
H
Department of Chemistry, Graduate School of Science, Kobe University, Rokko-dai, Nada-ku, Kobe 657-8501, Japan. haruki@kobe-u.ac.jp
Yabuguchi
Hiroki
H
Yamada
Yuji
Y
Fujihara
Akimasa
A
Fuke
Kiyokazu
K
D003198:Computer Simulation; D019281:Dimerization; D005453:Fluorescence; D007211:Indoles / Q000737:chemistry*; D008956:Models, Chemical; D011522:Protons; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
C023422:7-azaindole dimer; D007211:Indoles; D011522:Protons