… induced by two-photon double excitation of Ne2
On the 24th of March 2017, Tsukasa Takanashi gained his doctorate from the University of Tohoku (Japan), together with the President’s Award prize (総長賞). The prize is awarded each year to the best PhD students in recognition of their outstanding academic curriculum, and particularly for the excellent results obtained during their studies. Tsukasa carried out his studies under the supervision of Professor Kiyoshi Ueda, a leading figure on the international scene of atomic and molecular physics, and until recently, a member of the FERMI Review Panel. In his thesis, Tsukasa used the light from Free Electron Lasers (FELs) to study the dynamics of highly excited molecular systems; in his home country, he utilized the Japanese FEL SACLA, and he studied the Coulomb explosion of the molecule CH2I2 (diiodomethane). This process is the fragmentation by multiple ionization of a sample, and the successive repulsion of the ions by the positive charge which is generated.
An important part of his work was carried out at FERMI, currently the only FEL source in the world able to provide Tsukasa the wavelength (75.6 nm) and temporal resolution (10-13 s) necessary to study the dynamics of his system: the Ne2 molecule, which consists of two neon atoms bound by their weak van der Waals interaction. The apparent simplicity of this system allows the detailed study of complex phenomena, such as the exchange of energy after electronic excitation, which is basic to all photochemical processes.
Image: Schematic representation of the resonant absorption of two FEL photons by a neon dimer (upper panel) and the ICD relaxation process by ionization (lower panel).