High-Order Harmonic Photoelectron Spectroscopy System towards Measuring Attosecond Electron Dynamics on Solid Surfaces

摘要

With the aim of tracking the motion of electrons on semiconductor surfaces on an attosecond timescale, we have developed a femtosecond time-resolved surface photoelectron spectroscopy (PES) system based on a 59th harmonic pulse source, and a 90-eV high-order harmonic pulse source using a few-cycle carrier-envelope phase (CEP) stabilized laser pulse. We used this surface PES system to measure the time evolution of the surface photovoltage effect on GaAs(0 0 1). We observed an energy shift of about 200 meV of a 3d-core level photoelectron peak towards a higher binding energy. This suggests that the surface potential changed owing to the spatial separation of the electron-hole pair that was generated by laser irradiation. Our observation of the CEP dependence of the harmonic spectrum generated by the CEP-stabilized few-cycle pulse indicates that this source has the potential to produce an attosecond EUV pulse.