Molecular physics of elementary processes relevant to hypersonics: Electron-molecule collisions

Non-resonant, electron-impact, vibro-electronic excitation cross sections, involving vibrationally excited N2 molecules, to the mixed valence-Rydberg b,c,o 1Πu and b′,c′,e′ 1åu+ singlet states are presented. These cross sections are calculated using the so-called similarity approach, accounting for the vibronic coupling among excited states, and compared with the experiments and different theoretical calculations. New cross sections for the electron-impact resonant vibrational excitation of CO2 molecule are calculated, for the symmetric stretching mode, as a function of the incident electron energy and for the transitions (υ i , 0,0)→(νf , 0,0) with νi = 0,1,2 and for some selected value of νf in the interval νi ≤νf ≤10. A resonance potential curve and associated widths are calculated using the R-matrix method. Rate coefficients, calculated by assuming a Maxwellian electron energy distribution function, are also presented for the same (νi , 0,0)→(νf , 0,0) transitions. Electron-impact cross sections and rate coefficients for resonant vibrational excitations involving the diatomic species N2, NO, CO, O2 and H2, for multi-quantic and mono-quantic transitions, are reviewed along with the cross sections and rates for the process of the dissociative electron attachment to H2 molecule, involving a Rydberg excited resonant state of the H2- ion

Electron-impact vibrational excitation of vibrationally excited H2 molecules involving the resonant 2(Sigma)g+ Rydberg-excited electronic state

Electron-impact theoretical cross sections and rate coefficients for vibrational excitation of vibrationally excited H2 molecules, occurring through the H−2 resonant species in the 2Σ+g Rydberg-excited electronic state, are presented. The cross sections are calculated as functions of the incident electron energy by adopting the local-complex-potential model for resonant collisions and by using ab initio calculated molecular potentials and resonance widths. The calculations have been extended to all possible vibrational transitions linking all 15 vibrational levels of the electronic ground state of the H2 molecule. The corresponding rate coefficients are also obtained as a function of the electron temperature by assuming a Maxwellian electron energy distribution function, and a simple analytical expression is derived. Finally, the present rate coefficients for the transitions starting from the lowest vibrational level of the H2 molecule are compared with those for the process involving the X2Σ+u resonant state of the H−2 molecular ion

Atomic and molecular data for spacecraft re-entry plasmas

The modeling of atmospheric gas, interacting with the space vehicles in re-entry conditions in planetary exploration missions, requires a large set of scattering data for all those elementary processes occurring in the system. A fundamental aspect of re-entry problems is represented by the strong non-equilibrium conditions met in the atmospheric plasma close to the surface of the thermal shield, where numerous interconnected relaxation processes determine the evolution of the gaseous system towards equilibrium conditions. A central role is played by the vibrational exchanges of energy, so that collisional processes involving vibrationally excited molecules assume a particular importance. In the present paper, theoretical calculations of complete sets of vibrationally state-resolved cross sections and rate coefficients are reviewed, focusing on the relevant classes of collisional processes: resonant and non-resonant electron-impact excitation of molecules, atom-diatom and molecule-molecule collisions as well as gas-surface interaction. In particular, collisional processes involving atomic and molecular species, relevant to Earth (N2, O2, NO), Mars (CO2, CO, N2) and Jupiter (H2, He) atmospheres are considered

Reporting Recommendations for Tumor Marker Prognostic Studies (REMARK): Explanation and Elaboration

The REMARK “elaboration and explanation” guideline, by Doug Altman and colleagues, provides a detailed reference for authors on important issues to consider when designing, conducting, and analyzing tumor marker prognostic studies