Search results

Sort By:

Limit search:

Formation of a Complete Electron Transfer State of 9,9'-Bianthryl in a Polar Solvent

100%

Nishiyama K., Honda T., Okada T.

Acta Physica Polonica A

1998

vol. 94

issue 5-6

847-856

It has been generally recognized that excited 9,9'-bianthryl in polar solvents achieves a partial charge-separation state, instead of a complete electron transfer state, even in high-polarity solvents like acetonitrile at room temperature. However, here we firstly found that 9,9'-bianthryl reaches the complete electron transfer state in a polar alkanenitrile solvent at lower temperature as elucidated by means of transient absorption and steady-state fluorescence spectroscopy. A stepwise increase in the fluorescence Stokes shift observed when temperature was reduced implies a formation of a state more polar than that dominated at the room temperature. At low temperature (165 K), the transient absorption spectra of 9,9'-bianthryl in butyronitrile gradually changed from the spectrum ascribed to the partial change-separation state toward that of the complete electron transfer state. We suggest that at low temperature, due to the increase in the solvent polarity, the energetically stabilized electron transfer state should be predominant.

Photophysical Properties of Diphenylacetylene and Diphenylbutadiyne Derivatives in Solution Phase

100%

Hirata Y., Okada T., Nomoto T.

Acta Physica Polonica A

1998

vol. 94

issue 4

627-636

By using the femtosecond and picosecond transient absorption measurement techniques, we have investigated diphenylacetylene, diphenylbutadiyne, and their methoxy and cyano derivatives in the solution phase. Both the rapid S_{2} → S_{1} internal conversion in the subpicosecond time scale and the triplet formation in the tens of picosecond region were observed for diphenylbutadiyne and its methoxy derivatives, while the dynamic behavior of dimethoxy-diphenylacetylene was quite similar to that of diphenyl acetylene. The level inversion of the lowest excited singlet states of dicyano-diphenylbutadiyne was observed. The thermally activated S_{2} ← S_{1} internal conversion was not negligible and the sum of the rate constants of S_{2} → S_{1} and S_{2} ← S_{1} internal conversions was estimated to be about 5 × 10^{11} s^{-1} at room temperature.

Refine search results

2 Acta Physica Polonica A

2 1998

2 Okada T.

1 Hirata Y.

1 Honda T.

1 Nishiyama K.

1 Nomoto T.

Search results

Formation of a Complete Electron Transfer State of 9,9'-Bianthryl in a Polar Solvent

Photophysical Properties of Diphenylacetylene and Diphenylbutadiyne Derivatives in Solution Phase