arXiv subjects

Nayla El-Kork

Publications and source records attributed to Nayla El-Kork.

4 recordsLinked to original sources

arXiv2024

ExoMol line lists -- LXIV: Empirical rovibronic spectra of phosphorous mononitride (PN) covering the IR and UV regions

A new phosphorous mononitride (${}^{31}$P${}^{14}$N, ${}^{31}$P${}^{15}$N) line list PaiN covering infrared, visible and ultraviolet regions is presented. The PaiN line list extending to the $A\,{}^{1}Π$ -- $X\,{}^{1}Σ^{+}$ vibronic band system, replaces the previous YYLT ExoMol line list for PN. A thorough analysis of high resolution experimental spectra from the literature involving the $X\,{}^{1}Σ^{+}$ and $A\,{}^{1}Π$ states is conducted, and many perturbations to the $A\,{}^{1}Π$ energies are considered as part of a comprehensive MARVEL study. Ab initio potential energy and coupling curves from the previous work [Semenov et al., Phys. Chem. Chem. Phys., 23, 22057 (2021)] are refined by fitting their analytical representations to 1224 empirical energy levels determined using the MARVEL procedure. The PaiN line list is compared to previously observed spectra, recorded and calculated lifetimes, and previously calculated partition functions. The ab initio transition dipole moment curve for the $A$--$X$ band is scaled to match experimentally measured lifetimes. The line list is suitable for temperatures up to 5000 K and wavelengths longer than 121 nm. PaiN is available from www.exomol.com.

astro-ph.EP↗

arXiv2023

Quantum scattering cross sections of O($^3P$) + N$_2$ collisions for planetary aeronomy

"Hot atoms", which are atoms in their excited states, transfer their energy to the surrounding atmosphere through collisions. This process of energy transfer is known as thermalization, and it plays a crucial role in various astrophysical and atmospheric processes. Thermalization of hot atoms is mainly governed by the amount of species present in the surrounding atmosphere and the collision cross-section between the hot atoms and surrounding species. In this work, we investigated the elastic and inelastic collisions between hot oxygen atoms and neutral N$_2$ molecules, relevant to oxygen gas escape from the martian atmosphere and for characterizing the chemical reactions in hypersonic flows. We conducted a series of quantum scattering calculations between various isotopes of O($^3P$) atoms and N$_2$ molecules across a range of collision energies (0.3 to 4 eV), and computed both their differential and collision cross-sections using quantum time$-$independent coupled-channel approach. Our differential cross-section results indicate a strong preference for forward scattering over sideways or backward scattering, and this anisotropy in scattering is further pronounced at higher collision energies. By comparing the cross-sections of three oxygen isotopes, we find that the heavier isotopes consistently have larger collision cross-sections than the lighter isotopes over the entire collision energy range examined. However, for all the isotopes, the variation of collision cross-section with respect to collision energy is the same. As a whole, the present study contributes to a better understanding of the energy distribution and thermalization processes of hot atoms within atmospheric environments. Specifically, the cross$-$sectional data presented in this work is directly useful in improving the accuracy of energy relaxation modeling of O and N$_2$ collisions over Mars and Venus atmospheres.

astro-ph.EP↗

arXiv2022

A quantum-mechanical investigation of O($^3P$) + CO scattering cross sections at superthermal collision energies

The kinetics and energetic relaxation associated with collisions between fast and thermal atoms are of fundamental interest for escape and therefore also for the evolution of the Mars atmosphere. The total and differential cross-sections of fast O($^3P$) atom collisions with CO have been calculated from quantum mechanical calculations. The cross-sections are computed at collision energies from 0.4 to 5 eV in the center-of-mass frame relevant to the planetary science and astrophysics. All the three potential energy surfaces ($^3$A', $^3$A" and 2 $^3$A" symmetry) of O($^3P$) + CO collisions separating to the atomic ground state have been included in calculations of cross-sections. The cross-sections are computed for all three isotopes of energetic O($^3P$) atoms collisions with CO. The isotope dependence of the cross-sections are compared. Our newly calculated data on the energy relaxation of O atoms and their isotopes with CO molecules will be very useful to improve the modeling of escape and energy transfer processes in the Mars' upper atmosphere.

physics.chem-ph↗

arXiv2021

Rovibronic spectroscopy of PN from first principles

We report an ab initio study on the rovibronic spectroscopy of the closed-shell diatomic molecule phosphorous mononitride, PN. The study considers the nine lowest electronic states, $X\,{}^{1}Σ^{+}$, $A\,{}^{1}Π$, $C\,{}^{1}Σ^{-}$, $D\,{}^{1}Δ$, $E\,{}^{1}Σ^{-}$, $a\,{}^{3}Σ^{+}$, $b\,{}^{3}Π$, $d\,{}^{3}Δ$ and $e\,{}^{3}Σ^{-}$ using high level electronic structure theory and accurate nuclear motion calculations. The ab initio data cover 9 potential energy, 14 spin-orbit coupling, 7 electronic angular momentum coupling, 9 electric dipole moment and 8 transition dipole moment curves. The Duo nuclear motion program is used to solve the coupled nuclear motion Schrödinger equations for these nine electronic states and to simulate rovibronic absorption spectra of $^{31}$P$^{14}$N for different temperatures, which are compared to available spectroscopic studies. Lifetimes for all states are calculated and compared to previous results from the literature. The calculated lifetime of the $A\,{}^{1}Π$ state shows good agreement with an experimental value from the literature, which is an important quality indicator for the ab initio $A$-$X$ transition dipole moment.

physics.atom-ph↗