Aa. Avdeenko et al., LUMINESCENCE AND ODMR STUDIES OF X-TRAPS FOR TRIPLET EXCITONS IN ORGANIC-CRYSTALS, Low temperature physics, 23(3), 1997, pp. 247-250
The excited triplet states of shallow X-traps in neat single crystals
of 4,4'-dichlorobenzophenone were studied at liquid helium temperature
by luminescence spectroscopy and magnetic resonance with optical dete
ction. The vibrational phosphorescence bands, the polarization of phos
phorescence spectra, and the triplet zero-held splitting parameters of
these traps have been analyzed. A specific model of the structure def
ect (a molecule is turned by 180 degrees on its long axis) has been co
nsidered in organic crystals of benzophenone type which consist of mol
ecules whose dipole moments compensate each other in a unit cell. The
calculated depth of such a dipole X-trap for triplet excitons in Lf,4'
-dichlorobenzophenone crystals at the account of a defect molecule rel
axation upon its slewing was found to be comparable with the experimen
tal one. (C) 1997 American Institute of Physics.