Study on Electron Dynamics at Nanoscale Functional Films

Understanding of the electronic structure and photoexcited state dynamics at well-prepared layered functional materials on substrates is essentially important in order to precisely design and control the future electronic or optical nanodevices. I have been so far engaged in this research field experimentally from the view point of molecular science, where the electronic states and dynamics at nanoscale functional films fabricated with organic molecules and/or nanocluster superatoms are investigated by probing photoelectrons, combining with a femtosecond light source and with a nanocluster deposition system. In this account, firstly, I show the electronic structures and photoexcited state dynamics at two-dimensional (2D) molecular monolayer systems of alkanethiolate self-assembled monolayers by two-photon photoemission spectroscopy which clarifies novel ultrafast phenomena characteristic to the 2D assembly of the functional molecules. Secondly, I present the visualization of local photoexcited states in the organic films by changing the probe system into two-photon photoelectron emission microscopy. Finally, the electronic states and chemical properties of nanocluster superatoms as a new class of functional nanomaterials are explained, which are non-destructively landed onto the substrates.