Ultrafast and large reflectivity change by ultraviolet excitation of the metallic phase in the organic conductor (EDO-TTF)2PF6

We examined the ultrafast response of the metallic high-temperature phase in the conducting charge transfer complex (EDO-TTF)2PF6. A large reflectivity change of approximately 10% was observed when the intra-molecular band was excited by a weak 3.1 eV ultraviolet light pulse. The lifetimes of the photo-induced states were 0.2 and 0.7 ps in the Drude-like band and the intra-molecular band, respectively. Measurement of the photo-induced spectrum just after photo-excitation and simulation using the Drude model revealed that the electronically excited EDO-TTF molecules shortened the relaxation time of conduction electrons and reduced the reflectivity of the Drude-like band.