Magnetic effects on delayed fluorescence in doped naphthalene and anthracene crystals

Abstract

We have solved the density matrix equation for mutual triplet annihilation in some special cases. The solution allows a simple calculation of the magnetic field dependence of the annihilation rate γs for homofusion at high and intermediate magnetic fields and for heterofusion in the high field limit. In our experiments we have measured the magnetic field anisotropy of the guest delayed fluorescence in doped anthracene and naphthalene crystals. By using the resonance condition for heterofusion, the positions of the resonance peaks have been calculated. A comparison of the measured and calculated resonance directions shows that tetracene enters the anthracene lattice substitutionally oriented, whereas the orientation of pyrene molecules in naphthalene differs slightly from the substitutional one. Furthermore, we have shown that in the latter case the host–guest annihilation gives rise almost exclusively to guest delayed fluorescence, although the excitation of the host singlet state is energetically possible.

Triplet exciton transport in isotopic mixed naphthalene crystals. I. Kinetic analysis of trapping and fusion

“…It should be a good approximation for BMN/CIOHg heterofusion, however, since the orientations of the fine structure principal axes for the two species are very similar. 32 ) This partition function must be modified since the resultant singlet exciton has a 0.67 probability of converting back to the triplet state via intersystem crossing. 33 -35 Therefore, the final partition function for producing a singlet exciton is f~11 = 0.25X(1 -0.67) = O.OS.…”

Growth of 2,5-diphenyloxazole-doped naphthalene crystal by Bridgman method and its fluorescence studies

“…Literature survey shows that naphthalene has been doped by number of molecular crystals like anthracene [6][7][8][9][10], pyrene [6], tetracene [7,8,11], pentacene [12], 1,3-phenylenediamine, 1,4-toluidine, 1,3-toluidine, 1,2-toluidine, aniline, durene, 1,2-nitroaniline, hydroquinone, 1,3-nitroaniline, resorcin, toluene, 1,2-dibromobenzene, 1,2-dichlorobenzene, benzene [13], p-phenylstilbene, 1,2-di(beta-naphthyl)-ethylene, 1-(beta-naphthyl)-2-(pbyphenyl)-ethylene [14], dibenzoterrylene [15]. In this paper, we report on 2,5-diphenyloxazole (PPO)-doped naphthalene crystal growth and evaluation of its properties with four different PPO mole concentrations.…”

Accessibility of the lowest quintet state of organic molecules through triplet-triplet annihilation; an indo ci study

“…The magnetic-field dependence of hetero-TTA in molecular crystals has been investigated experimentally and theoretically [95,96]. Examples of delayed fluorescence resulting from hetero-TTA in liquid solutions are known (from S, [97] and from upper excited singlet states [92,98]).…”