Photo-commutation de solides moléculaires
Author | : Johan Hebert |
Publisher | : |
Total Pages | : 40 |
Release | : 2009 |
ISBN-10 | : OCLC:690249151 |
ISBN-13 | : |
Rating | : 4/5 (51 Downloads) |
Book excerpt: The present work deals with the photoinduced switching studies of several molecular materials and the underlying mechanisms. In a first part, crystallographic studies of photoinduced quasi-stationary states of spin transition compounds are presented. The comparison between the response of [Fe(PM-BiA)2(NCS)2] polymorphs, [(TPA)Fe(TCC)]PF6 polymorphs and the [Fe(DPEA)(NCS)2] compound in this material class allowed to highlight various mechanisms during the thermally and photoinduced spin state change, according to the amplitude of intermolecular coupling. In a second part, photo-switching studies of the [(TPA)Fe(TCC)]PF6 compound, generated by a femtosecond laser pulse and the associated ultrafast structural dynamic are presented. The picoseconds X-ray diffraction experiments allowed the in-depth study of the out-of-equilibrium dynamic where two major step are evidenced: an ultrafast photo-switching followed by a microsecond thermal switching. Finally, precursor cooperative phenomena study of photoinduced phase transition during neutral to ionic transition of TTF-CA by means of time resolved diffuse scattering measurements is addressed. Results associated to experimental developments made it possible to highlight the pretransitonal mechanism one-dimensional aspect.