Abstract

In nature, light drives many important processes, such as photosynthesis and vision. Light-driven processes are also important in technology, such as in nanoscale electronic devices. At the heart of all these processes are small chromophores that absorb light and, subsequently, undergo small-scale structural changes. Understanding the fundamental photophysics and photochemistry of the chromophores that determine the efficiency of light-driven processes in nature and technology is crucial for the rational design of new photomaterials for a range of applications such as photovoltaics and bioimaging. In addition to a detailed knowledge of the intrinsic electronic structures of these chromophores, it is important to have an understanding of the roles of their environments.

Experimentally, a direct way of probing electronic structure is through the measurement of electron binding energies using photoelectron spectroscopy (PES). Liquid-microjet UV PES is emerging as a valuable probe of the electronic structure of weakly soluble organic chromophores in solution. This seminar will begin with an introduction to PES , a brief review of the history of liquid-microjet photoelectron spectroscopy and a discussion of some the challenges facing UV PES of liquids. It will follow on with a brief description of the design and operation of the recirculating liquid-microjet PES instrument we have built at UCL for studying samples that are available in relatively small quantities and a discussion of illustrative liquid-microjet PES measurements of fluorescent protein chromophores and their building blocks.