Accession Number : AD0691026

Title :   TEMPERATURE EFFECTS ON INTERSYSTEM CROSSING IN NAPHTHALENE,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Jones,Peter F. ; Calloway,A. R.

Report Date : 21 MAY 1969

Pagination or Media Count : 27

Abstract : The fluorescence lifetime, t for naphthalene-h8 is the same in seven different solvents at room temperature. Upon cooling to 77K, however, t increases by 50 to 100 percent, depending upon the solvent matrix. For naphthalene-h8 in poly(methyl methacrylate) (PMM), we have also measured the temperature dependence of the fluorescence yield and of the quantum yield for intersystem crossing. These measurements show that variations in the rate constant for intersystem crossing are primarily responsible for the variations with temperature of t for naphthalene-h8 in PMM. Our results suggest that there may be another temperature-dependent nonradiative mode of decay of the fluorescent singlet state S1; however, our experiments do not permit an unambiguous verification of this decay mode. Identical measurements for naphthalene-d8 suggest that internal conversion from S1 to the ground singlet state is negligible at all temperatures. All of the temperature, solvent, and deuteration effects on t can be explained in terms of intersystem crossing from S1 to a triplet state slightly lower in energy than S1. (Author)

Descriptors :   (*NAPHTHALENES, *FLUORESCENCE), ELECTRON TRANSITIONS, RELAXATION TIME, ORGANIC SOLVENTS, ACRYLIC RESINS, MOLECULAR ENERGY LEVELS

Subject Categories : Radiation and Nuclear Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE