Accession Number : ADP008249

Title :   Hole Burning in the Organic Triplet State: Side Holes in an Amorphous Glass,

Corporate Author : AUSTRALIAN NATIONAL UNIV CANBERRA

Personal Author(s) : Riesen, Hans ; Krausz, Elmars

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : Hole-burning spectroscopy has been widely applied to the S sub 0 -S sub 1, transition of organic molecules in amorphous hosts. However, only very few reports on the hole-burning spectroscopy of the triplet state have appeared. The low oscillator strength of the S sub 0 -T sub 1 transition is the obvious handicap in performing such experiments. The oscillator strength of the S sub O -T sub 1, transition can be dramatically increased by the heavy atom effect making hole-burning experiments in the S sub O -T sub 1, transition more feasible. A very pronounced heavy atom effect can be expected in ligand-centered singlet -triplet transitions of second and especially third row transition metal complexes leading to lifetimes in the iis range. In the hole-burning spectrum of the S sub O -T sub 1, transition it is in principal possible to observe side-holes that are separated from the resonant feature by +/-D for a chromophore with D not = O and E not = O and by +/-D+E), +/-D-E) an +/-2E for a molecule with D not = O and E not = O. However, the first excited singlet state S sub 1 and the phosphorescent triplet state T sub 1 are well known to be poorly correlated in glasses, i.e. the S sub 1-T sub 1 separation is not constant within the inhomogeneous distribution. The spin sublevels of the triplet state may also not be correlated. In the case of a varying ZFS within the inhomogeneous distribution, side-holes will be broader than the resonant feature. If this variation is large enough, no distinct side features can be observed.

Descriptors :   *MOLECULAR SPECTROSCOPY, *GLASS, ATOMS, CHROMOPHORES, LIGANDS, METAL COMPLEXES, METALS, MOLECULES, OSCILLATORS, SPECTROSCOPY, TRANSITION METALS, AMORPHOUS MATERIALS.

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE