Evidence of dynamic Jahn-Teller distortions in two-dimensional crystalline molecular films

Authors

Jaewu Choi, University of Nebraska-LincolnFollow
Peter A. Dowben, University of Nebraska-LincolnFollow
C.N. Borca, University of Nebraska-Lincoln
Shireen Adenwalla, University of Nebraska-LincolnFollow
A.V. Bune, University of Nebraska-Lincoln
Stephen Ducharme, University of NebraskaFollow
V.M. Fridkin, Institute of Crystallography, The Russian Academy of Sciences, 117333 Moscow, Russia
S.P. Palto, Institute of Crystallography, The Russian Academy of Sciences, 117333 Moscow, Russia
N. Petukhova, Institute of Crystallography, The Russian Academy of Sciences, 117333 Moscow, Russia

Date of this Version

1-15-1999

Comments

Published by American Physical Society. Copyright 1999. Permission to use. Phys. Rev. B 59 (1999) 1819-1824. http://prb.aps.org/

Abstract

The surface electronic structure in crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%) has been studied by photoemission and inverse photoemission as a function of alkali metal (sodium) doping. Sodium doping introduces at least two new states into the band (HOMO-LUMO) gap well away from the Fermi level. While the sodium-doped copolymer is observed to resemble an n-type semiconductor, the change in electronic structure with temperature suggests that dynamic distortions lead to a photoemission initial state splitting of the lower Hubbard-like bands. There is a decrease in the effective Debye temperature with sodium doping which may, in turn, enhance the dynamic Jahn-Teller distortion.