Theoretical Study of Inelastic Processes in Collisions of Y and Y$^+$ with Hydrogen Atom

TL;DR

This study uses a quantum model to calculate inelastic collision rates between yttrium atoms/ions and hydrogen atoms at low energies, providing data crucial for astrophysical plasma modeling.

Contribution

It presents detailed rate coefficients for multiple inelastic processes in Y and Y$^+$ with H, considering extensive states and symmetries, which is novel for these collision systems.

Findings

Rate coefficients peak at 6000K for mutual neutralization.

Optimal collision energy windows are near specific electronic binding energies.

Data are useful for non-LTE astrophysical modeling.

Abstract

Utilizing a simplified quantum model approach, the low-energy inelastic collision processes between yttrium atoms (ions) and hydrogen atoms have been studied. Rate coefficients corresponding to the mutual neutralization, ion-pair formation, excitation, and de-excitation processes for the above collision systems have been provided in the temperature range of 1000-10000K. 3 ionic states and 73 covalent states are considered in calculations for the collisions of yttrium atoms with hydrogen atoms, which include 6 molecular symmetries and 4074 partial inelastic reaction processes. For the collisions of yttrium ions with hydrogen atoms, 1 ionic state and 116 covalent states are included, which related to 3 molecular symmetries and 13572 partial inelastic collision processes. It is found that the rate coefficients for the mutual neutralization process have a maximum at T = 6000K, which is an order of magnitude higher than those of other processes. Notably, the positions of optimal windows for the collisions of yttrium atoms and ions with hydrogen atoms are found near electronic binding energy -2eV (Y) and -4.4eV (Y$^+$), respectively. The scattering channels located in or near these optimal windows have intermediate-to-large rate coefficients (greater than $10^{-12}$ cm$^3$s$^{-1}$). The reported data should be useful in the study of non-local thermodynamic equilibrium modeling.