Luis Miaja-Avila

Angle-resolved photoemission spectroscopy with a femtosecond high harmonic light source using a two-dimensional imaging electron analyzer

An experimental setup for time- and angle-resolved photoemission spectroscopy using a femtosecond 1 kHz high harmonic light source and a two-dimensional electron analyzer for parallel energy and momentum detection is presented. A selection of the 27th harmonic (41.85 eV) from the harmonic spectrum of the light source is achieved with a multilayer MoSi double mirror monochromator. The extinction efficiency of the monochromator in selecting this harmonic is shown to be better than 7:1, while the transmitted bandwidth of the selected harmonic is capable of supporting temporal pulse widths as short as 3 fs. The recorded E(k) photoelectron spectrum from a Cu(111) surface demonstrates an angular resolution of better than 0.6 degrees (=0.03 A(-1) at E(kin,e)=36 eV). Used in a pump-probe configuration, the described experimental setup represents a powerful experimental tool for studying the femtosecond dynamics of ultrafast surface processes in real time.

Laser-assisted photoemission from surfaces driven by long-wavelength infrared light

We demonstrate experimentally the advantages of driving laser-assisted photoemission from surfaces with long-wavelength-IR light. We show that applications in probing surface dynamics benefit from using longer-wavelengths since many side effects of strong fields are suppressed.

Direct measurement of core-level relaxation dynamics on a surface-adsorbate system using ultrafast x-rays

We present the first direct measurement of inner shell relaxation dynamics on complex systems, in this case an adsorbate on a surface. We measured a lifetime of 7 fs for N-shell vacancies of Xe on Pt(111).

Laser-Assisted Photoelectric Effect on Pt(111)

We observe the laser-assisted photoelectric effect on a surface for the first time. Simultaneously illuminating Pt(111) with the fundamental and 27th harmonic of a Ti:sapphire femtosecond laser results in energy modulation of the photoelectron spectrum.