We study the photon emission by bremsstrahlung and nonlinear Compton scattering from interaction of ultra-intense laser pulses with cone target and flat foil using particle-in-cell simulations. The simulations are performed for laser pulses interacting with Al and Au targets. The strength of the two mechanisms of photon emission from bremsstrahlung and nonlinear Compton scattering are compared. When an ultra-intense (I>10^{22}W/cm^{2}) laser interacts with a cone and a foil target, photon emission by bremsstrahlung is found to be comparable to that from nonlinear Compton scattering. The obtained electron energy as well as the energy and number of photons emitted were found to be higher in case of cone shaped target compared with that of a foil target. The enhanced photon emission from cone shaped target is attributed to the guiding or collimation of hot electrons towards the cone tip from the self-generated magnetic field and electrostatic field along the cone surface which pushes the hot electrons towards the tip.
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http://dx.doi.org/10.1103/PhysRevE.105.025205 | DOI Listing |
J Fluoresc
January 2025
Department of Physics, Jnanabharathi, Bangalore University, Bengaluru, 560056, Karnataka, India.
In this report the photophysical property of newly synthesized fluorescein based derivative 2-(5-((2,4-dichlorophenyl)diazenyl)-6-hydroxy-3-oxo-3H-xanthen-9-yl)benzoic acid has studied by spectroscopic and theoretical that is by Density Functional Theory technique. The structural and functional group of the synthesized molecule was confirmed by nuclear magnetic resonance and fourier transform infrared spectroscopy technique, and from the result so far obtained has been confirmed that molecule has a stable structure and confirmed the presence the functional groups present in the sample. The optical properties of the molecule are studied using the spectroscopic technique and it has revealed the solute-solvent interaction behaviour of the molecule and it has been observed that the bathochromic shift was of about 5 nm, from the fluorescence measurement it has revealed that the emission has been observed at green region and from the power spectra it has been confirmed the same.
View Article and Find Full Text PDFInt J Comput Assist Radiol Surg
January 2025
Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA.
Purpose: Pulmonary perfusion imaging is a key lung health indicator with clinical utility as a diagnostic and treatment planning tool. However, current nuclear medicine modalities face challenges like low spatial resolution and long acquisition times which limit clinical utility to non-emergency settings and often placing extra financial burden on the patient. This study introduces a novel deep learning approach to predict perfusion imaging from non-contrast inhale and exhale computed tomography scans (IE-CT).
View Article and Find Full Text PDFACS Photonics
January 2025
Department of Physics, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, Pennsylvania 15218, United States.
We report the canonical properties of the Bose-Einstein condensation of polaritons in the weak coupling regime, seen previously in many low-temperature experiments, at room temperature in a GaAs/AlGaAs structure. These effects include a nonlinear energy shift of the polaritons, showing that they are not noninteracting photons, and dramatic line narrowing due to coherence, giving coherent emission with a spectral width of 0.24 meV at room temperature with no external stabilization.
View Article and Find Full Text PDFACS Photonics
January 2025
Foundation of Research and Technology Hellas, Institute of Electronic Structure and Laser, Heraklion 71110, Greece.
We demonstrate a simple, low-cost, and ultracompact chiral resonant metasurface design, which, by strong local coupling to a quantum gain medium (quantum emitters), allows to implement an ultrathin metasurface laser, capable of generating tunable circularly polarized coherent lasing output. According to our detailed numerical investigations, the lasing emission can be transformed from linear to circular and switch from right- to left-handed circularly polarized (CP) not only by altering the metasurface chiral response but also by changing the polarization of a linearly polarized pump wave, thus enabling dynamic lasing-polarization control. Given the increasing interest for CP laser emission, our chiral metasurface laser design proves to be a versatile yet straightforward strategy to generate a strong and tailored CP emission laser, promising great potential for future applications in both photonics and materials science.
View Article and Find Full Text PDFNatl Sci Rev
February 2025
Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
Organic red/near-infrared (NIR) room-temperature phosphorescence (RTP) holds significant potential for autofluorescence-free bioimaging and biosensing due to its prolonged persistent luminescence and exceptional penetrability. However, achieving activatable red/NIR organic RTP probes with tunable emission in aqueous solution remains a formidable challenge. Here we report on aqueous organic RTP probes with red/NIR phosphorescence intensity and lifetime amplification.
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