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Transient photocurrents induced by time‐dependent diffusion of excitons to the surface of anthracene and p‐chloranil single crystals
Author(s) -
Killesreiter H.,
Braun R.
Publication year - 1971
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220480119
Subject(s) - anthracene , chloranil , exciton , diffusion , chemistry , quenching (fluorescence) , singlet state , effective diffusion coefficient , materials science , molecular physics , condensed matter physics , atomic physics , optics , photochemistry , physics , fluorescence , thermodynamics , excited state , medicine , radiology , magnetic resonance imaging
Transient photocurrents produced by a light flash were used as a probe for the time‐dependent diffusion of excitons in anthracene and p‐chloranil single crystals. An analytical solution for the time‐dependent diffusion equation for excitons near a quenching phase boundary is presented. Inserting experimental data allows evaluation of the lifetime, τ = 4×10 −6 s, the diffusion coefficient, D = 5×10 −6 cm 2 /s, and hence the diffusion length, L = 5×10 −6 cm, for n‐π* triplet excitons diffusing perpendicular to ( ab ) planes in p‐chloranil. For triplet excitons in anthracene, the diffusion coefficient normal to ( ab ) plane, D ≈ 5 × 10 −5 cm 2 /s, is estimated. The method allows to distinguish between different sorts of excitons diffusing in a crystal with different velocities. This is of importance for anthracene, where both singlet and triplet excitons are produced by strongly absorbed light.