Accession Number:

ADA235884

Title:

Dynamic Solvent Effects on Electron Transfer Rates in the Inverted Regime: Ultrafast Studies on the Betaines

Descriptive Note:

Technical rept.

Corporate Author:

MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMISTRY

Report Date:

1991-05-06

Pagination or Media Count:

28.0

Abstract:

Transient pump-probe measurements have been made on Betaine-30, the solvent polarity probe. Betaine-30 is composed of organic donor and acceptor groups. The transient data has been analyzed to measure k sub et the electron transfer et rate constant, in polar solvents for this inverted regime et. The observed rate constant, in various polar solvents is as much as a factor of 100, 000 larger than is predicted by the standard, classical, implementation of the theory of Sumi and Marcus, using Kjaer and Ulstrups estimates for necessary parameters. In contrast, a quantum treatment of the vibrational modes by Jortner and Bixon, which includes the dynamic solvent effect, predicts that the rate should be approximately k sub et, JB1 tau sub s. This is close to the experimental results in typical polar aprotic solvents. The kinetic behavior of Betaine-30 in slowly relaxing solvents is shown to be in the diffusionless limit of the hybrid, generalized Sumi-MarcusJortner-Bixon picture.

Subject Categories:

  • Organic Chemistry
  • Physical Chemistry
  • Radiation and Nuclear Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE