A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution

We present the development of a versatile apparatus for 6.2 eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved mu-ARPES). With a combination of tunable spatial resolution down to similar to 11 mu m, high energy resolution ( similar to 11 meV), near-transform-limited temporal resolution (similar to 280 fs), and tunable 1.55 eV pump fluence up to 3 mJ/cm(2), this time-resolved mu-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved mu-ARPES on a similar to 30 mu m flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.