Related papers: Depolarizing collisions with hydrogen: neutral and…
Interpretations of the very rich second solar spectrum of the MgH molecule face serious problems owing to the complete lack of any information about rates of collisions between the MgH and hydrogen atoms. This work seeks to begin the…
Simulations of the generation of the atomic polarization is necessary for interpreting the second solar spectrum. For this purpose, it is important to rigorously determine the effects of the isotropic collisions with neutral hydrogen on the…
Results. We consider the problem of isotropic collisions between an alkali atom and neutral hydrogen. We calculate the collisional tensorial components of general p and s-states, characterized by their effective principal quantum number…
Context: The scattering polarization of the infrared (IR) triplet of neutral oxygen (O\,\textsc{i}) near 777\,nm provides a powerful diagnostic of solar atmospheric conditions. However, interpreting such polarization requires a rigorous…
Our work is concerned with the case of the solar molecule CN which presents conspicuous profiles of scattering polarization. We start by calculating accurate PES for the singlet and triplet electronic ground states in order to characterize…
The physical interpretation of scattering line polarization offers a novel diagnostic window for exploring the thermal and magnetic structure of the quiet regions of the solar atmosphere. Here we evaluate the impact of isotropic collisions…
Neutral and singly ionized states of the Magnesium (Mg) are the origin of several spectral lines that are useful for solar diagnostic purposes. An important element in modeling such solar lines is collisional data of the Mg with different…
Analysis of solar magnetic fields using observations as well as theoretical interpretations of the scattering polarization is commonly designated as a high priority area of the solar research. The interpretation of the observed polarization…
This paper is a continuation of a series of studies investigating collisional depolarization of solar molecular lines like those of MgH, CN and C$_2$. It is focused on the case of the solar molecule C$_2$ which exhibits striking scattering…
Rigorous implementation of the effects of collisions in modeling the formation of the polarized solar lines is of utmost importance in order to realistically analyze the available, highly sensitive solar spectropolarimetric observations.…
Context. Rigorous modeling of the \ion{Ba}{ii} ${\lambda}4554$ formation is potentially interesting since this strongly polarized line forms in the solar chromosphere where the magnetic field is rather poorly known. Aims. To investigate the…
Scattering and ionizing cross sections and rates are calculated for ultracold collisions between metastable helium atoms using a fully quantum-mechanical close-coupled formalism. Homonuclear collisions of the bosonic ${}^{4}$He$^{*}…
Chromospheric and prominence plasmas contain neutral atoms, which may change the plasma dynamics through collision with ions. Most of the atoms are neutral hydrogen, but a significant amount of neutral helium may also be present in the…
We study hydrogen plasmas at magnetic fields B ~ 10^{12}-10^{13} Gauss, densities ~ 10^{-3}-10^3 g/cc and temperatures T ~ 10^{5.5}-10^{6.5} K, typical of photospheres of middle-aged cooling neutron stars. We construct an analytical free…
Although the spectral lines of hydrogen contain valuable information on the physical properties of a variety of astrophysical plasmas, including the upper solar chromosphere, relatively little is known about their scattering polarization…
Recently, the production of ultrahigh-density (~10^{19}cm^{-3}) spin-polarized deuterium (SPD) atoms was demonstrated, from the photodissociation of deuterium iodide, but the upper density limit was not determined. Here, we present studies…
We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable (2 3S1) 3He and 4He atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713 (2006)]. A…
Solar photosphere and chromosphere are composed of weakly ionized plasma for which collisional coupling decreases with height. This implies a breakdown of some hypotheses underlying magnetohydrodynamics at low altitudes and gives rise to…
We explore the potential energy surfaces for NH molecules interacting with alkali-metal and alkaline-earth atoms using highly correlated ab-initio electronic structure calculations. The surfaces for interaction with alkali-metal atoms have…
Ultracold neutral plasmas, formed by photoionizing laser-cooled atoms near the ionization threshold, have electron temperatures in the 1-1000 kelvin range and ion temperatures from tens of millikelvin to a few kelvin. They represent a new…