Abstract
We present energy-resolved measurements of electron emission from sharp metal tips driven with low energy pulses from a few-cycle laser oscillator. We observe above-threshold photoemission with a photon order of up to 9. At a laser intensity of the suppression of the lowest order peak occurs, indicating the onset of strong-field effects. We also observe peak shifting linearly with intensity, with a slope of around . We attribute the magnitude of the laser field effects to field enhancement taking place at the tip’s surface.
- Received 13 September 2010
DOI:https://doi.org/10.1103/PhysRevLett.105.257601
© 2010 The American Physical Society