Ultrafast studies of electronic processes at surfaces using the laser-assisted photoelectric effect with long-wavelength dressing light

We show that ultrafast surface science studies using the laser-assisted photoelectric effect can benefit from longer-wavelength infrared dressing beams. We compare soft-x-ray photoemission from a Pt(111) surface dressed by 1300 and 780 nm light. Using 1300 nm light, the amplitude of the laser-assisted photoelectric signal is enhanced sevenfold compared with 780 nm. This allows lower dressing laser intensity to be used, which dramatically suppresses undesirable processes such as above-threshold photoemission, desorption, and distortion of the photoemission spectrum due to space charge. This work enables ultrafast studies of surface-adsorbate systems and attosecond electron dynamics over a wider energy range.