There is no consensus on the magnitude and shape of the charge transfer cross section in low-energy H þ þ H 2 collisions, in spite of the fundamental importance of these collisions. Experiments have thus been carried out in the energy range 15 E 5000 eV. The measurements invalidate previous recommended data for E 200 eV and confirm the existence of a local maximum around 45 eV, which was predicted theoretically. Additionally, vibrationally resolved cross sections allow us to investigate the evolution of the underlying charge transfer mechanism as a function of E.

We report a theoretical-experimental investigation of electron scattering by dichloromethane (CH 2 Cl 2) in the low-and intermediate energy ranges. Experimental elastic differential cross sections (DCS), in the incident electron energy range of 0.5-800eV and scattering angle range of 10°-130°, were measured using a crossed beam relative flow technique. Integral and momentumtransfer cross sections were determined from the experimental DCS. Theoretical elastic differential, integral, and momentum-transfer, as well as grand-total, and total absorption cross sections were also calculated for impact energies ranging from 0.5 to 500eV. A complex optical Hartree-Fock potential represented the electron-target interaction and a single-center expansion method combined with a Padé approximation was used to solve the scattering equations. Three resonances: a 2 A 1 C-Cl kσ * resonance centered at about 3.5eV, a 2 B 2 C-Cl kσ * resonance centered at about 5eV and a broad 2 A 1 C-H kσ * resonance at about 10eV were detected in our calculation. Further calculations of DCS were performed at an intermediate energy range of 50-800eV, using the independent-atom model in which the atomic complex optical potential and partial-wave method were used to obtain atomic scattering amplitudes. Comparisons of our experimental and theoretical data with very recent experimental and theoretical results are made.

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The electron impact X 1 Σ g + → b 3 Σ u + transition in molecular hydrogen is one of the most important dissociation pathways to forming atomic hydrogen atoms, and is of great importance in modeling astrophysical and industrial plasmas where molecular hydrogen is a substantial constituent. Recently it has been found that the convergent close-coupling (CCC) cross sections of Zammit et al. [Phys. Rev. A 95, 022708 (2017)] are up to a factor of two smaller than the currently recommended data. We have determined normalized differential cross sections for excitation of this transition from our experimental ratios of the inelastic to elastic scattering of electrons by molecular hydrogen using a transmission-free time-of-flight electron spectrometer, and find excellent agreement with the CCC calculations. Since there is already excellent agreement for the absolute elastic differential cross sections, we establish new recommended differential and integrated cross sections with theory and experiment being essentially in complete agreement-unprecedented for differential electron impact excitation of any molecular transition to date.