The dynamics of an electron bunch irradiated by two focused colliding super-intense laser pulses and the resulting γ and e(-)e(+) production are studied. Due to attractors of electron dynamics in a standing wave created by colliding pulses the photon emission and pair production, in general, are more efficient with linearly polarized pulses than with circularly polarized ones. The dependence of the key parameters on the laser intensity and wavelength allows us to identify the conditions for the cascade development and γe(-)e(+) plasma creation.
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http://dx.doi.org/10.1103/PhysRevE.93.023207 | DOI Listing |
Nanoscale
January 2025
Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata-700106, India.
Herein, we investigated the carrier-phonon relaxation process in a two-dimensional (2D) BAPbBr perovskite and its heterostructure with MoS. Energy transfer was observed in the van der Waals heterostructure of 2D perovskite and monolayer MoS, leading to enhancement in the photoluminescence intensity of MoS. Femtosecond pump-probe spectroscopy was used to study the carrier and lattice dynamics of pristine 2D materials and their heterostructure.
View Article and Find Full Text PDFMagn Reson Med
January 2025
Oxygen Measurement Core, O2M Technologies, LLC, Chicago, Illinois, USA.
Purpose: Solid crystalline spin probes, such as lithium phthalocyanine (LiPc) and lithium octa-n-butoxynaphthalocyanine (LiNc-BuO), allow repeated oxygen measurement using electron paramagnetic resonance (EPR). Due to their short relaxation times, their use for pulse EPR oxygen imaging is limited. In this study, we developed and tested a new class of solid composite spin probes that modified the relaxation rates R and R of LiPc or LiNc-BuO probes, which allowed pO measurements in the full dynamic (0-760 torr) range.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Abteilung für Molekulare Physikalische Chemie, Clausius-Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Wegelerstraße 12, 53115 Bonn, Germany.
The binding of carbon dioxide to a transition metal is a complex phenomenon that involves a major redistribution of electron density between the metal center and the triatomic ligand. The chemical reduction of the ligand reveals itself unambiguously by an angular distortion of the CO-molecule as a result of the occupation of an anti-bonding π-orbital and a shift of its antisymmetric stretching vibration, ν, to lower wavenumbers. Here, we generate a carbon dioxide complex of the heavier group-10 metal, platinum, by ultrafast electronic excitation and cleavage of CO from the photolabile oxalate precursor, oxaliplatin, and monitored the ensuing primary dynamics with ultrafast mid-infrared spectroscopy.
View Article and Find Full Text PDFDalton Trans
January 2025
Institute for Organic Synthesis and Photoreactivity (ISOF) - National Research Council (CNR), Via P. Gobetti 101, 40129 Bologna, Italy.
A supramolecular system, consisting of a tetrapyrenylporphyrinic core surrounded by arene-ruthenium prisms, has been assembled and characterized by means of electrochemical and photophysical techniques. The photophysical study shows that quantitative energy transfer from the peripheral pyrenyl units towards the central porphyrin core is operative in the tetrapyrenylporphyrinic system. Interestingly, encapsulation of the pyrenyl units into the ruthenium cages affects the photophysics of the central porphyrin component, since its emission quantum yield is reduced in the supramolecular array.
View Article and Find Full Text PDFNanoscale
January 2025
Research Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Loading cocatalysts on semiconductor-based photocatalysts to create active reaction sites is a preferable method to enhance photocatalytic activity and a widely adopted strategy to achieve effective photocatalytic applications. Although theoretical calculations suggest that the broad density of states of noble metal cocatalysts, such as Pt, act as a recombination center, this has never been experimentally demonstrated. Herein, we employed pico-nano and nano-micro second transient absorption spectroscopy to investigate the often overlooked photogenerated holes, instead of the widely studied electrons on Pt- and Ni-loaded SrTiO to evaluate the effects of cocatalysts as a recombination center.
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