Pb. Lukins, Direct observation of semiconduction and photovoltaic behaviour in single molecules of the Photosystem II reaction centre, CHEM P LETT, 321(1-2), 2000, pp. 13-20
Scanning tunnelling spectroscopy of single intact Photosystem II molecules
was used to directly show that the reaction centre behaves as an organic se
miconductor and photovoltaic. The main electron conduction mechanisms obser
ved were (a) semiconduction associated with the normal step-wise linear for
ward electron transfer pathway OEC-Y-z-P680-pheo-Q(A)-Q(B), (b) a photovolt
aic effect, (c) tunnelling to surface vibronic and delocalized states, and
(d) hopping conduction between polypeptide residues. Parameters for these c
onduction processes were obtained for both dark and illuminated conditions.
The photovoltaic behaviour of the reaction centre contrasts with the photo
conductive behaviour of the associated light-harvesting complex LHC-II. (C)
2000 Elsevier Science B.V. All rights reserved.