98%
921
2 minutes
20
Time-resolved momentum microscopy is an emerging technique based on photoelectron spectroscopy for characterizing ultrafast electron dynamics and the out-of-equilibrium electronic structure of materials in the entire Brillouin zone with high efficiency. In this article, we introduce a setup for time-resolved momentum microscopy based on an energy-filtered momentum microscope coupled to a custom-made high-harmonic generation photon source driven by a multi-100 kHz commercial Yb-ultrafast laser that delivers fs pulses in the extreme ultraviolet range. The laser setup includes a nonlinear pulse compression stage employing spectral broadening in a Herriott-type bulk-based multi-pass cell. This element allows flexible tuning of the driving pulse duration, providing a versatile time-resolved momentum microscopy setup featuring two operational modes designed to enhance either the energy or time resolution. We show the capabilities of the system by tracing ultrafast electron dynamics in the conduction band valleys of a bulk crystal of the 2D semiconductor WS. Using uncompressed driving laser pulses, we demonstrate an energy resolution better than (107 ± 2) meV, while compressed pulses lead to a time resolution better than (48.8 ± 17) fs.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11775307 | PMC |
http://dx.doi.org/10.1038/s41598-025-86660-1 | DOI Listing |
IUCrJ
September 2025
Institut de Biologie Structurale, 38000 Grenoble, France.
Time-resolved neutron scattering has been used to study dynamically polarized protons in tyrosyl-doped bovine liver catalase. While the evolution of proton polarization and its inversion by the method of adiabatic fast passage (AFP) in a standard dynamic nuclear polarization (DNP) system with organic Cr(V) complexes can be well modelled and understood, the experiments with tyrosyl-doped catalase lead us into the world of extremely dilute paramagnets with only about 10 unpaired electrons per cm. In this regime, the strength of DNP is comparable to the drift of proton polarization towards its thermal equilibrium of P = 0.
View Article and Find Full Text PDFOpt Express
April 2025
We investigate the dynamics of a driven-dissipative polariton condensate in a GaAs microcavity under simultaneous excitations by a continuous laser and a pulsed laser. The femtosecond pulse destabilizes and quenches the condensate, which is then followed by a nonlinear luminescence surplus. Time-resolved photoluminescence shows a ring-like pattern in momentum space that shrinks as the condensate relaxes back to its steady state.
View Article and Find Full Text PDFJ Synchrotron Radiat
September 2025
Department of Physics and Astronomy, Uppsala University, PO Box 516, SE-75120 Uppsala, Sweden.
A grazing-incidence Rowland spectrometer with a collimating element for resonant inelastic soft X-ray scattering at the Veritas beamline at MAX IV, Lund, Sweden, is presented. The instrument is designed to operate in the 250-950 eV range, providing >30000 resolving power in first order. The inherent temporal resolution of the delay-line detector enables time-resolved experiments on the 270 ps time-scale and also allows for so-called time-gating which significantly improves the signal-to-noise ratio.
View Article and Find Full Text PDFIUCrJ
September 2025
ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxford OX11 0QX, United Kingdom.
High-quality total scattering data, a key tool for understanding atomic-scale structure in disordered materials, require stable instrumentation and access to high momentum transfers. This is now routine at dedicated synchrotron instrumentation using high-energy X-ray beams, but it is very challenging to measure a total scattering dataset in less than a few microseconds. This limits their effectiveness for capturing structural changes that occur at the much faster timescales of atomic motion.
View Article and Find Full Text PDFNat Commun
July 2025
MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an, 710049, China.
Proton transfer underpins number of chemical and biochemical processes, yet its sub-100 fs dynamics have rarely been captured in real time. Here, we report direct and time-resolved observation of ionizing radiation-induced proton transfer in a heteroaromatic hydrate: the pyrrole-water complex. Both the electron-impact and strong-field laser experiments create a locally and doubly charged pyrrole unit (CHN), which immediately (within 60 fs) donates a proton to the adjacent HO, generating deprotonated CHN and hydronium HO cations that subsequently undergo Coulomb explosion.
View Article and Find Full Text PDF