Tunable ultrafast extreme ultraviolet source for time- and angle-resolved photoemission spectroscopy

Abstract

We present a laser-based apparatus suitable for visible pump/extreme UV (XUV) probe time-, energy-, and angle-resolved photoemission spectroscopy utilizing high-harmonic generation from a noble gas. Tunability in a wide range of energies (currently 20-36 eV) is achieved by using a time-delay compensated monochromator, which also preserves the ultrashort duration of the XUV pulses. Using an amplified laser system at 10 kHz repetition rate, approximately 10(9)-10(10) photons/s per harmonic are made available for photoelectron spectroscopy. Parallel energy and momentum detection is carried out in a hemispherical electron analyzer coupled with an imaging detector. First applications demonstrate the capabilities of the instrument to easily select the probe wavelength of choice, to obtain angle-resolved photoemission maps (GaAs and URu(2)Si(2)), and to trace ultrafast electron dynamics in an optically excited semiconductor (Ge).