Attosecond electron dynamics on solid surfaces

本项目将探索固体超快光激发的测量和控制。其目标是在阿秒时间尺度和原子长度尺度上获得对固体表面附近光电子动力学的新见解。这些动力学涉及许多复杂和相互关联的现象，目前尚不清楚，但对当前和未来纳米级量子设备、太阳能电池、传感器和表面的催化作用的功能是基本的。一些相关的过程及其特征时间标度是：费米边缘热电子的热正态化(10s Of F)，电子从离域和局域核态到表面的输运时间(&lt；1f)，电子从吸附原子到衬底的电荷转移(&lt；1f)，电荷屏蔽和成像电荷产生(&lt；1f)，团簇中的直接和间接电子散射(&lt；1f到f)。这个项目将解决的关键问题包括：(I)在金属或半导体内部发射的光电子波包是如何传播到表面的，在什么时间尺度上？(Ii)吸附层如何改变光激发和电子波包的传播？(3)是否可以通过调整样品和光学波形，在纳米尺度和几飞秒到阿秒的时间尺度上控制表面的光电子发射和光电流？

This project will explore the measurement and control of ultrafast photo-excitation of solids. The goal is to obtain new insight into the dynamics of photoelectrons near the surfaces of solids on the attosecond time-scale and atomic length scale. These dynamics involve a number of complex and interconnected phenomena that are currently not well understood, but are fundamental to the function of current and future nanoscale quantum devices, solar cells, sensors and the catalytic action of surfaces. Some of the relevant processes and their characteristic timescales are: thermalisation of hot electrons at the Fermi edge (10s of fs), transport time for electron from delocalised and localised core-states to surface (<1fs), charge transfer of electrons from adsorbed atom to substrate (<1fs), charge screening and image charge creation (<1fs), direct and indirect electron scattering in clusters (<1fs to fs). Key questions that this project will address include:(i) How do photoelectron wavepackets launched inside a metal or semiconductor propagate to the surface and on what timescales? (ii) How are the photo-excitation and electron wavepacket propagation modified by adsorbate layers? (iii) Can photoelectron emission and photocurrents from surfaces be controlled on the nanoscale and on the few femtosecond to attosecond timescales by tailoring both samples and optical waveforms?