Accession Number : AD0695706

Title :   PHOTOPHYSICAL PROCESSES IN MOLECULAR SOLIDS.

Descriptive Note : Final rept. 16 Mar 66-12 May 68,

Corporate Author : CALIFORNIA UNIV RIVERSIDE DEPT OF CHEMISTRY

Personal Author(s) : Kearns,David R.

Report Date : 01 SEP 1969

Pagination or Media Count : 48

Abstract : It is generallly presumed that the photochemistry of aromatic ketones proceeds from the lowest triplet state of the molecule, but if the second triplet state lies near the lowest triplet state, then it could play a role in room temperature photochemistry. Because of the intrinsic weakness of the S to T(pi,pi) compared to the S to T(n,pi) transition, and the small splitting between the singlet (n,pi) and triplet (n,pi) states it is not surprising that the singlet (pi,pi) state has not been located in an aromatic ketone where the triplet (n,pi) state is the lowest excited state. In the present work an attempt was made to overcome this difficulty by making use of the fact that S to T(pi,pi) transitions are selectively enhanced both by internal and external heavy-atom perturbations, and by carrying out the measurements both at 77K and 4K on single crystals. (Author)

Descriptors :   (*BENZOPHENONES, *MOLECULAR ENERGY LEVELS), (*PHOSPHORESCENCE, BENZOPHENONES), (*PHOTOCHEMICAL REACTIONS, BENZOPHENONES), ELECTRON TRANSITIONS, SINGLE CRYSTALS, ULTRAVIOLET SPECTRA, VISIBLE SPECTRA, ACETOPHENONES

Subject Categories : Radiation and Nuclear Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE