The ASTRA end-station

Angle-resolved photoelectron spectroscopy or ARPES, is a key-technique for characterizing solids, and enables researchers to study the electronic band structure of single crystalline materials. Of particular relevance are electrons at the so-called Fermi surface, the most sensitive to external stimuli, which determine the electronic properties of materials interesting for their quantum properties and promising for future applications.
The Harmonium short pulses can be employed to perform ARPES with time-resolution (trARPES) where electrons are set in motion by a secondary light pulse, revealing fundamental interactions and meta-stable states not observable in equibrium conditions.
ARPES experiments are extremely demanding in terms of sample contamination, and require a dedicated ultra-high vacuum chamber, ASTRA (ARPES Spectrometer for Time-Resolved Applications) , developed by the LSE group and currently managed by LACUS personnel and the SOIS group. User acces is provided to EPFL and external users.

Photoemission main chamber of ASTRA, showing the motorized sample manipulator and the electron energy analyser entrance electronic lens.

Time-resolved ARPES at LACUS: Band Structure and Ultrafast Electron Dynamics of Solids

A. Crepaldi; S. Roth; G. Gatti; C. A. Arrell; J. Ojeda et al. 

CHIMIA International Journal for Chemistry. 2017-05-01. Vol. 71, num. 5, p. 273-277. DOI : 10.2533/chimia.2017.273.