991 research outputs found
Methods and Apparatus for Predicting Performance of a Measurement Method, Measurement Method and Apparatus
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Development of a 300 Hz Terawatt NOPCPA System for a Tabletop High Flux Coherent Soft X-Ray Source
No full textEffect of soil temperature on optical frequency transfer through unidirectional dense-wavelength-division-multiplexing fiber-optic links
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Diffractive shear interferometry for extreme ultraviolet high-resolution lensless imaging
No full textPublications, presentations and other activities Effect of soil temperature on one-way optical frequency transfer through dense-wavelength-division-multiplexing fibre links 2015
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Probing excitons with time-resolved momentum microscopy
No full textExcitons – two-particle correlated electron-hole pairs – are the dominant low-energy optical excitation in the broad class of semiconductor materials, which range from classical silicon to perovskites, and from two-dimensional to organic materials. The study of excitons has been brought on a new level of detail by the application of photoemission momentum microscopy – a technique that has dramatically extended the capabilities of time- and angle resolved photoemission spectroscopy. Here, we review how the photoelectron detection scheme enables direct access to the energy landscape of bright and dark excitons, and, more generally, to the momentum-coordinate of the exciton wavefunction. Focusing on two-dimensional materials and organic semiconductors, we first discuss the typical photoemission fingerprint of excitons in momentum microscopy and highlight that it is possible to obtain information not only on the electron- but also hole-component. Second, we focus on the recent application of photoemission orbital tomography to such excitons, and discuss how this provides a unique access to the real-space properties of the exciton wavefunction. We detail how studies performed on two-dimensional transition metal dichalcogenides and organic semiconductors lead to very similar conclusions, and, in this manner, highlight the strength of momentum microscopy for the study of optical excitations in semiconductors
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