Related papers: Ortho-para-H$_2$ conversion processes in astrophys…
Ortho-to-para (o/p) ratios of species like water, ammonia and formaldehyde (H2CO) are believed to encode information about the formation history of the molecule. Measurements of o/p ratios in protoplanetary disks could thus be used to…
Two different ab initio potential energy surfaces are employed to investigate the efficiency of the rotational excitation channels for the polar molecular ion HeH$^+$ interacting with He atoms. We further use them to investigate the quantum…
Rate coefficients for inelastic Mg+H collisions are calculated for all transitions between the lowest seven levels and the ionic state (charge transfer). The rate coefficients are based on cross-sections from full quantum scattering…
We study binary and the recently discovered process of ternary He-assisted recombination of H3+ ions with electrons in a low temperature afterglow plasma. The experiments are carried out over a broad range of pressures and temperatures of…
Astrophysical models of primordial star formation require rate constants for three-body recombination as input. The current status of these rates for H2 due to collisions with H is far from satisfactory, with published rate constants…
Context. Molecular hydrogen and its cation H+2 are among the first species formed in the early Universe, and play a key role in the thermal and chemical evolution of the primordial gas. In molecular clouds, H+2 ions formed through…
We have reviewed the chemistry and cooling behaviour of low-density (n<10^4 cm^-3) primordial gas and devised a cooling model wich involves 19 collisional and 9 radiative processes and is applicable for temperatures in the range (1 K < T <…
Context. In dffuse interstellar clouds the excitation temperature derived from the lowest levels of H$^+_3$ is systematically lower than that derived from H2. The differences may be attributed to the lack of state-specific formation and…
We report the detection of the 1_{10}-1_{11} ground state transition of ortho-H_2D^+ at 372.421 GHz in emission from the young stellar object NGC 1333 IRAS 4A. Detailed excitation models with a power-law temperature and density structure…
Rate coefficients for inelastic collisions between Li and H atoms covering all transitions between the asymptotic states Li(2s,2p,3s,3p,3d,4s,4p,4d,4f)+H(1s) and Li^+ +H^- are presented for the temperature range 2000-8000 K based on recent…
LiCu_2O_2 single crystals were studied in the temperature range 300-1100 K by means of heating-cooling curves of differential thermal analysis (DTA), thermogravimetry (TG), X-ray powder diffraction and electrical measurements. A reversible…
We construct the velocity map images of the proton transfer reaction between helium and molecular hydrogen ions H2+. We perform simulations of imaging experiments at one representative total collision energy taking into account the inherent…
Cold cores in interstellar molecular clouds represent the very first phase in star formation. The physical conditions of these objects are studied in order to understand how molecular clouds evolve and how stellar masses are determined. The…
Molecular hydrogen is the most abundant molecular species in the Universe. While no doubts exist that it is mainly formed on the interstellar dust grain surfaces, many details of this process remain poorly known. In this work, we focus on…
The reactions of cold H atoms with solid O2 molecules were investigated at 10 K. The formation of H2O2 and H2O has been confirmed by in-situ infrared spectroscopy. We found that the reaction proceeds very efficiently and obtained the…
We have calculated the rate coefficients for D(1s) + H^+ <--> D^+ + H(1s) using recently published theoretical cross sections. We present results for temperatures T from 1 K to 2x10^5 K and provide fits to our data for use in plasma…
Formic acid (HCOOH) and carbon dioxide (CO2) are simple species that have been detected in the interstellar medium. The solid-state formation pathways of these species under experimental conditions relevant to prestellar cores are primarily…
The triatomic hydrogen ion H3+ is one of the most important species for the gas phase chemistry of the interstellar medium. Observations of H3+ are used to constrain important physical and chemical parameters of interstellar environments.…
The Orion Bar is one of the nearest and best-studied photodissociation or photon-dominated regions (PDRs). Observations reveal the presence of H2 lines from vibrationally or rotationally excited upper levels that suggest warm gas…
Reactive cross-sections for the collision of open shell S(^1D) atoms with ortho- and para-hydrogen, in the kinetic energy range 1-120 K, have been calculated using the hyperspherical quantum reactive scattering method developed by Launay et…