Akinori Inoue

Time resolved spectra of pyrene excimer and pyrene-dimethylaniline exciplex

Abstract Time-resolved fluorescence spectra were measured for pyrene and for the pyrene-N,N-dimethylaniline system in the range from 3 nsec to 150 nsec after the excitation by a nitrogen gas laser. By the aid of the spectra, we could follow the formation and decay processes of the pyrene excimer or the pyrene-N,N-dimethlaniline exciplex. The rate constants were determined for the exciplex formation and decay processes.

The Bimolecular Annihilation of Excitons and Singlet-Excition Migration in Anthracene Crystals

Abstract The mechanism of exciton migration in anthracene crystals was studied by measuring a rate constant, γ, for the bimolecular annihilation of exitons at various temperatures between 5°K and 250°K. Consequently, γ was found to be proportional to 1/√T. This is in accordance with the band model for the exciton motion. The present method for the study of the singlet-exciton migration, which is free from the trapping effect by impurity-induced lattice defects and from the host-guest interaction effect, is superior to the usual method using host-guest systems.

Triplet dynamics of benzaldehyde as studied by electron impact excitation

Abstract Electron-impact-induced luminescence was measured for benzaldehyde at low vapor pressure. Phosphorescence bands from the zero-point level of T 1 were observed at 397.427, and 460 nm. The pressure dependence of the phosphorescence decay rate was found to be essentially the same as that obtained by optical excitation. In addition to these bands, closely spaced, weak emission bands were observed. These emissions were found to have much shorter lifetimes than the phosphorescence from the zero-point level and to be sensitive to collisional quenching. We assign the latter bands to the phosphorescence from vibrationally excited T 1 molecules.

Effect of high density excitons on fluorescence of naphthalene-tetracyanobenzene complex crystal

Abstract An exciton-exciton collisional annihilation was studied with the naphthalene-tetracyanobenzene complex crystal by observing and analyzing the fluorescence decay curve; the second-order decay constant was determined to be 3 × 10−13 cm3 sec−1 at 77°K. A new type of inhomogeneous broadening effect was found for the fluorescence from the complex crystal excited in high density and was interpreted to be due to the strong electrostatic interaction between the charge-transfer excitons with large dipole moments.

Triplet-state dynamics at low pressures as studied by electron-impact-induced phosphorescence: Acetophenone

Abstract Electron-impact-induced phosphorescence was observed for acetophenone at pressures between 3.2 and 48 mTorr. In addition to normal phosphorescence from the T1 zero-point level, we observed phosphorescence from vibrationally excited T1 molecules at lower pressures. Collisional quenching of the triplet levels is discussed based on the pressure dependence of the phosphorescence. Excitation functions were measured for these two kinds of phosphorescence and the mechanism of triplet-state formation is discussed.

Electron-impact luminescence spectra and neutral fragments: Identification of neutral fragments by use of fragment emissions

Electron-impact luminescence spectra were measured for cyclohexanol, acetic acid, pyridine, pyrimidine, benzonitrile, aniline, nitrobenzene, p-methoxy-nitrobenzene, 1-chlorobutane, 1-chloropentane, tetrahydrofuran and anisole. The spectra were analyzed and compared with the literature data of mass spectrometry. It was found that fragment emissions of OH(A2Σ+-X2Π), CN(B2Σ-X2Σ), NO(B2Π-X2Π) and HCl+(A2Σ-X2Π) can be used for the identification of neutral fragments of OH and H2O, HCN, NO and HCl, respectively.

Electron-impact-induced luminescence and triplet-state dynamics of acetone and perdeuterated acetone at low pressures

Abstract Luminescence from acetone and acetone- d 6 has been investigated at pressures of 3.4–13 mTorr under electron impact. The decay curves of both compounds are found to be composed of two or three components depending on pressure. The decay rates and time-resolved spectra have been measured for the respective components as functions of pressure, and the nature of the states responsible for these emission components is discussed in relation to triplet-state dynamics.

Electron-impact-induced phosphorescence and mechanism of triplet-state formation in biacetyl

Abstract Electron-impact-induced phosphorescence of biacetyl was observed at low vapor pressures. Excitation functions and decay characteristics of the phosphorescence were measured as functions of pressure. Mechanisms of triplet formation under electron impact are discussed in terms of these results as well as previously reported electron spectroscopic data.