Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes

We review the different excitation processes in the interstellar mediumComment: Accepted in Chem. Re

Theoretical Study of Substitution of Si for Ge in Mn5\text{}_{5}Ge3\text{}_{3}

The substitution of silicon for germanium in Mn$\text{}_{5}$Ge$\text{}_{3}$ leads to a decrease in the magnetization for x < 0.7 and then to phase transition toward a non-collinear antiferromagnetic order for Mn$\text{}_{5}$Si$\text{}_{3}$. The magnetic properties of Mn$\text{}_{5}$Ge$\text{}_{3}$ and Mn$\text{}_{5}$(Ge$\text{}_{0.5}$Si$\text{}_{0.5}$)$\text{}_{3}$ are analyzed by means of band structure calculations

Ro-vibrational excitation of SiS by He

International audienc

Superconductivity, Weak Itinerant Ferromagnetism and Electronic Band Structure of Y 9

The paper presents experimental results for the intermetallic compound Y$\text{}_{9}$Co$\text{}_{7}$ which is the first very weak itinerant ferromagnetic superconductor. The measurements of electrical resistivity, susceptibility, magnetization, specific heat, nuclear magnetic resonance, and other properties show the magnetic transition at T$\text{}_{C}$≈ 4.5 K and the onset of superconductivity at about T$\text{}_{S}$≈ 2.5 K, revealing the coexistence state within a temperature interval below T$\text{}_{S}$. A few of the results are shortly reviewed and discussed. We focus attention on our recent ultraviolet photoemission spectroscopy and their comparison with our band structure calculations. Interpretations are considered which take into account the characteristic structure of the compound and different possible types of magnetic ordering

Superconductivity, Weak Itinerant Ferromagnetism and Electronic Band Structure of Y9\text{}_{9}Co7\text{}_{7}

The paper presents experimental results for the intermetallic compound Y$\text{}_{9}$Co$\text{}_{7}$ which is the first very weak itinerant ferromagnetic superconductor. The measurements of electrical resistivity, susceptibility, magnetization, specific heat, nuclear magnetic resonance, and other properties show the magnetic transition at T$\text{}_{C}$≈ 4.5 K and the onset of superconductivity at about T$\text{}_{S}$≈ 2.5 K, revealing the coexistence state within a temperature interval below T$\text{}_{S}$. A few of the results are shortly reviewed and discussed. We focus attention on our recent ultraviolet photoemission spectroscopy and their comparison with our band structure calculations. Interpretations are considered which take into account the characteristic structure of the compound and different possible types of magnetic ordering

Rotational excitation and de-excitation of PN molecules by He atoms

Context.Observations of molecular emission at millimeter and infrared wavelengths, supplemented by careful and detailed modeling, are powerful tools for investigating the physical and chemical conditions of astrophysical objects. Modeling of molecular emission requires the calculation of rates for excitation by collisions with the most abundant species. Aims.The present paper focuses on the calculation of rate coefficients for rotational excitation of the PN molecule in its ground vibrational state in collision with He, based on a new two-dimensional potential energy surface from highly correlated ab initio calculations. Methods.Calculations of pure rotational (de)excitation of PN by He were performed for the first rotational levels using the essentially exact close-coupling method for the lower levels and the coupled-states approximation for higher levels. Results.Cross sections for transitions among the 31 first rotational levels of PN were calculated for kinetic energies up to 2500 cm-1. These cross sections were used to determine collisional rate constants for temperatures ranging from 5 K to 300 K. A propensity for even $\Delta j$ transitions is observed, which reflects the nearly symmetric character of the PN-He potential energy surface

Magnetoelastic Properties of MnRhAs1−x\text{}_{1-x}px\text{}_{x} and Band Structure Results from KKR-CPA

The magnetoelastic phase transitions were observed in MnRhAs$\text{}_{1-x}$P$\text{}_{x}$ system (space group P6̅2m) by X-ray measurements (80 K < T < 300 K). For x = 0.33 and x = 0.4 contents an abrupt change of both lattice parameters and of the elementary cell volume at the metamagnetic transition was detected. The Korringa-Kohn-Rostoker electronic structure calculations performed for MnRhP compound show significant variations of densities of states at the Fermi level, while changing lattice data. The Korringa-Kohn- Rostoker-coherent potential approximation studies of disordered MnRhAs$\text{}_{1-x}$P$\text{}_{x}$ system (x=0.6, 0.8, 1.0) were done at the ferromagnetic region. From our calculations we observe moving of bands near E$\text{}_{F}$, while substituting with isoelectronic metalloid, likely as while changing the crystal data in MnRhP

Magnetic and Transport Properties of (Fe1−x\text{}_{1-x}Nix\text{}_{x})2\text{}_{2}P in View of KKR-CPA Results

We present results of the electronic structure study for the solid solution (Fe$\text{}_{1-x}$Ni$\text{}_{x}$)$\text{}_{2}$P (space group P6̅2m). The samples were synthesized for x=0.0 up to 0.15. From the electrical conductivity measurements on these materials, it was verified that resistivity increases with increasing temperature up to the Curie point T$\text{}_{C}$ and changes the slope at T$\text{}_{C}$ decreasing when temperature is raised above T$\text{}_{C}$. To get insight into the possible origin of such observations, we carried out the Korringa-Kohn-Rostoker-coherent potential approximation electronic structure calculations for (Fe$\text{}_{1-x}$Ni$\text{}_{x}$)$\text{}_{2}$P in the range of concentration x=0.0 up to 1.0. It was found that alloying with Ni in Fe$\text{}_{2}$ P causes vanishing of spin band splitting and non-rigid band behaving of electronic valence states near the Fermi level. The polarization factor for electrons at E$\text{}_{F}$ changes in (Fe$\text{}_{1-x}$Ni$\text{}_{x}$)$\text{}_{2}$P with increasing x, and interestingly, it reaches maximum at x=0.1, closely to the concentration (x=0.08), when the largest value of T$\text{}_{C}$ and a kink in temperature dependent resistivity were detected

Can we estimate H2\mathsf{_{2}}( j = 0) rate coefficients from He rate coefficients? Application to the SiS molecule

International audienc