Soft Matter Meets Ultrafast Spectroscopy
Abstract:
Although matter is divided in the three well-defined categories solid, liquid, and gas, there are certain states not exclusively belonging to either one of these categories. Liquid crystals (LCs) are one of these meta-phases, ordered like solids but fluid like liquids. Since their first discovery in 1888 by Friedrich Reinitzer, LCs raised an ever-increasing interest. LCs, in fact, present unique properties in terms of birefringence, high polarizability and the easy tunability in space and time by applying external stimuli like electric or magnetic fields, resulting in their vast exploitation in the present-day technology. LCs are just one example of the systems belonging to the much wider class of materials called "soft matter", which includes everything that is easily deformed from polymers to gels and colloids. So far, the physics of phenomena occurring in the ultrafast time scale, namely from picosecond down to attosecond, in soft matter and in particular LCs, where the electrons and fast vibrational modes play the dominant role, is largely unexplored. In these four days I will introduce you to the soft matter world and to the spectroscopic tools currently available to study them in the ultrafast time scale, meaning from picosecond down to attosecond. I will conclude showing you our new-born research activity at ULCD, where LCs meet ultrafast!