Date&Time: July 14, 12:00-12:35
Place: UVSOR Build. #304 (User's room)

Speaker: Prof. V.G. Stankevich
Affiliation: Russian Research Centre Kurchatov Institute, Russia and
UVSOR Facility, Institute for Molecular Science

Title: Optical investigations ferroelectric ordering C60F18 single crystals

Abstract: These nana objects-molecules C60F18 manifested very interesting
structures, having a deformed spherical C60 skeleton, surrounded 18
fluorine atoms occupy only one half of that. This is leading to a high
dipole moment, more then 10D. In principle it is possible to arrange a
ferroelectric ordering at the Curie temperature TC about 100K for
ensemble of these polar molecules in the Crystal, caused by dipole-dipole
interaction.
In unique one domain single crystals it has been observed IR spectra for
different light polarization and defined space orientation molecules in
crystal unit cell. It has been investigate for rectangular plane size 100
*60 microns2 temperature dependence of reflectivity in visible and VUV
energy regions. The luminescence spectra change drastically with cool
down, appears strong vibration structure, corresponding to IR
excitations. Analysis all temperature dependence dates are demonstrating
the possible face transition to new type ferroelectric state.