We systematically study the fluence dependence of the resonant scattering cross-section from magnetic domains in Co/Pd-based multilayers. Samples are probed with single extreme ultraviolet (XUV) pulses of femtosecond duration tuned to the Co M_{3,2} absorption resonances using the FERMI@Elettra free-electron laser. We report quantitative data over 3 orders of magnitude in fluence, covering 16 mJ/cm^{2}/pulse to 10 000 mJ/cm^{2}/pulse with pulse lengths of 70 fs and 120 fs. A progressive quenching of the diffraction cross-section with fluence is observed. Compression of the same pulse energy into a shorter pulse-implying an increased XUV peak electric field-results in a reduced quenching of the resonant diffraction at the Co M_{3,2} edge. We conclude that the quenching effect observed for resonant scattering involving the short-lived Co 3p core vacancies is noncoherent in nature. This finding is in contrast to previous reports investigating resonant scattering involving the longer-lived Co 2p states, where stimulated emission has been found to be important. A phenomenological model based on XUV-induced ultrafast demagnetization is able to reproduce our entire set of experimental data and is found to be consistent with independent magneto-optical measurements of the demagnetization dynamics on the same samples.
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http://dx.doi.org/10.1103/PhysRevLett.125.127201 | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
December 2024
Guangxi Key Laboratory of Drug Discovery and Optimization, Guangxi Engineering Research Center for Pharmaceutical Molecular Screening and Druggability Evaluation, School of Pharmacy, Guilin Medical University, Guilin 541199, PR China. Electronic address:
Resonance Light Scattering (RLS) is a sensitive analytical technology hindered by its susceptibility to impurities in complex samples. This study introduces a combination of RLS with a high-efficiency sample preparation device, the Miniaturized Thermal-Assisted Purge-and-Trap (MTAPT), enhancing RLS's effectiveness in complex sample analysis. Specifically, we utilized MTAPT-RLS for the indirect screening of illegal hydrochloride drug additions in health products, based on three considerations: the transformation of bound HCl in hydrochloride drugs into volatile HCl under strong acid and heat; the minimal Cl content in health products for taste purposes; and the detectability of Cl ions by RLS upon the addition of AgNO and a stabilizer.
View Article and Find Full Text PDFSci Adv
December 2024
Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA.
Most molecules and dielectric materials have characteristic bond vibrations or phonon modes in the mid-infrared regime. However, infrared absorption spectroscopy lacks the sensitivity for detecting trace analytes due to the low quantum efficiency of infrared sensors. Here, we report mid-infrared photothermal plasmonic scattering (MIP-PS) spectroscopy to push the infrared detection limit toward nearly a hundred molecules in a plasmonic nanocavity.
View Article and Find Full Text PDFJ Synchrotron Radiat
January 2025
Institute Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Straße 15, 12489 Berlin, Germany.
Resonant inelastic X-ray scattering (RIXS) is an ideal X-ray spectroscopy method to push the combination of energy and time resolutions to the Fourier transform ultimate limit, because it is unaffected by the core-hole lifetime energy broadening. Also, in pump-probe experiments the interaction time is made very short by the same core-hole lifetime. RIXS is very photon hungry so it takes great advantage from high-repetition-rate pulsed X-ray sources like the European XFEL.
View Article and Find Full Text PDFNanoscale
December 2024
Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, Campinas, SP 13083-859, Brazil.
We use non-resonant Raman scattering to demonstrate a large enhancement of the effective refractive index experienced by Raman photons in a scattering medium comprising spatially-correlated photonic structures of core-shell TiO@Silica scatterers mixed with silica nanoparticles and suspended in ethanol. We show that the high refractive index extends outside the physical boundary of the medium, which is attributed to the evanescent contributions of electromagnetic modes that are strongly localized within the medium. Notably, the effective enhancement can be observed even at very low intensities of Raman emission.
View Article and Find Full Text PDFJ Phys Chem A
December 2024
Division of Electron Collisions Physics, Institute of Physics and Applied Computer Science, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, ul. Gabriela Narutowicza 11/12, 80-233 Gdańsk, Poland.
The absolute total cross section for electron collisions with acetic acid has been measured using an electrostatic electron spectrometer and linear transmission method for collision energies ranging from 0.4 to 300 eV. Elastic electron scattering from acetic acid within a low-energy range has also been studied theoretically using the Schwinger multichannel and R-matrix methods, in the static-exchange and static-exchange plus polarization levels of approximation for energies up to 15 eV.
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