Study of Role of Large-Amplitute Vibrations in Dynamics of Molcular Complexes

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 10440168
• Research Category: Grant-in-Aid for Scientific Research (B).
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: TAKAYANAGI Masao Tokyo University of Agriculture and Technology, Graduate School of Bio-applications and Systems Engineering, Associate Professor, 大学院・生物システム応用科学研究科, 助教授 (50192448)
• Project Period (FY): 1998 – 2000
• Keywords: supersonic jet / laser spectroscopy / molecular complex / large-amplitude vibration / relaxation process / methyl torsional motion / intermolecular vibration / aromatic molecules

Research Abstract

Vacuum chamber for molecular beam experiment equipped with a linear time-of-flight mass spectrometer was constructed to measure mass-selected resonance multi-photon ionization spectra. With the equipment and another vacuum chamber for laser-induce fluorescence (LIF) purpose, following researches have been performed.
1. LIF-excitation spectra of methyl-substituted nitrogen-containing aromatic molecules such as picolines, methylpyrazine and methylquinoline in supersonic jets were measured. Relation between quantum yields of fluorescence and methyl torsional motion was studied.
2. LIF-excitation and dispersed fluorescence spectra of 4-dimethylaminopyridine and its 3-methyl and 3, 5-dimethyl derivatives in supersonic jets were measured. These molecules are known to have CT emission in polar solvents. Effects of methyl substitution at pyridine ring and of complex formation with some solvent molecules on CT-state formation were discussed.
3. LIF-excitation and hole-burning spectra of 5-methylin dole monomer and its complexes with H_2O, N_2O, methanol and benzene in supersonic jets were measured. Change of the torsional potential of methyl group of 5-methylindole upon complex formation was investigated.
4. LIF-excitation and hole-burning spectra of m-tolunitrile-N_2O and m-tolunitrile-H_2O complexes in supersonic jets were measured. For each complex, two isomers were found. Torsional potentials of methyl groups of m-tolunitrile-N_2O and m-tolunitrile-H_2O in one isomer were found to be almost similar with that in monomer. Out the other hand, torsional potentials in the other isomer are different appreciably from that in monomer. Torsional potentials in these complexes were compared with those in m-tolunitrile-rare gas complexes which had been determined previously.
5. LIF-excitation and hole-burning spectra of a merocyanine dye, NK1247, were measured. Origin of observed low-frequency bands were investigated. Low quantum yield of fluorescence for the dye molecule was discussed in terms of high efficiency photoisomerization of the molecule.