We report fully quantum calculations of the collisional perturbation of a molecular line for a system that is relevant for Earth's atmosphere. We consider the N-perturbed pure rotational R(0) line in CO. The results agree well with the available experimental data. This work constitutes a significant step toward populating the spectroscopic databases with ab initio collisional line-shape parameters for atmosphere-relevant systems. The calculations were performed using three different recently reported potential energy surfaces (PESs). We conclude that all three PESs lead to practically the same values of the pressure broadening coefficients.
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http://dx.doi.org/10.1063/5.0040438 | DOI Listing |
Phys Rev E
October 2024
Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA.
The relaxation of a weakly collisional plasma, which is of fundamental interest to laboratory astrophysical plasmas, can be described by the self-consistent Boltzmann-Poisson equations with the Lenard-Bernstein collision operator. We perform a perturbative (linear and second-order) analysis of the Boltzmann-Poisson equations and obtain exact analytic solutions which resolve some longstanding controversies regarding the impact of weak collisions on the continuous spectra, the discrete Landau eigenmodes, and the decay of plasma echoes. We retain both damping and diffusion terms in the collision operator throughout our treatment.
View Article and Find Full Text PDFJ Proteome Res
December 2024
Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States.
Owing to the role of the 20S proteasome in a wide spectrum of pathologies, including neurodegenerative disorders, proteasome-associated autoinflammatory syndromes (PRAAS), and cardiovascular diseases, understanding how its structure and composition contribute to dysfunction is crucial. As a 735 kDa protein assembly, the 20S proteasome facilitates normal cellular proteostasis by degrading oxidized and misfolded proteins. Declined proteasomal activity, which can be attributed to perturbations in the structural integrity of the 20S proteasome, is considered one of the main contributors to multiple proteasome-related diseases.
View Article and Find Full Text PDFPhys Rev E
September 2024
Department of Physics, Atomic and Laser Physics sub-department, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
Dense, hot plasmas are susceptible to the electrothermal instability: a collisional process which permits temperature perturbations in electron currents to grow. It is shown here that linearizing a system comprised of two opposing currents and a mobile ion background as three distinct fluids yields unstable modes with rapid growth rates (∼10^{13}s^{-1}) for wavenumbers below a threshold k_{th}. An analytical threshold condition is derived, this being surpassed for typical hot-spot and shell parameters.
View Article and Find Full Text PDFPhys Chem Chem Phys
October 2024
LSAMA, University of Tunis El-Manar, Tunis 1060, Tunisia.
We present quantum coupled-state calculations for the rotational excitation of interstellar propargylimine due to collisions with helium. The calculations are based on new high-accurate three-dimensional potential energy surfaces (3D-PESs) adapted for rigid-rotor scattering computations. The two PESs (/-PGIM-He) were determined using the explicitly correlated coupled-cluster approach with single, double and perturbative triple excitation [CCSCD(T)-F12] and the standard aug-cc-pVTZ basis set.
View Article and Find Full Text PDFJ Chem Phys
August 2024
Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, 67100 L'Aquila, Italy.
We investigate the contribution of inelastic electron collisions to nonlinear (NL) dynamics in ultraviolet plasmonic nanoparticles, exploring their potential for harmonic generation. Employing the Landau weak coupling formalism to model radiation-driven electron dynamics in sodium and aluminum, we account for both electron-electron and electron-phonon scattering processes by a set of hydrodynamic equations, which we solve perturbatively to obtain third-order NL susceptibilities. Furthermore, we model high harmonic generation enhanced by localized surface plasmons in nanospheres composed of such poor metals, demonstrating their efficient operation for extreme ultraviolet generation.
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