ISSN:
1434-601X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract State-resolved measurements are presented for vibrational excitation of H2, N2, O2 and CO2 by H− impact in the collision energy rangeE cm=20–180 eV and for scattering in the forward direction (0±0.5°). The data obtained from the measurements are the relative intensities and differential cross sections for vibrational excitation up toν′=4, the transition probabilitiesP 0→ν′ and the vibrational energy transferΔE vib. For the systems H−-H2, N2, O2 the vibrational inelasticity increases in the order H2-N2-O2. The mechanism for vibrational excitation in these systems is due to transient charge transfer from the H− ion into antibonding orbitals of the target molecule which provides a bond stretching force during the collision. For H2 and N2, the results are compared with corresponding measurements for H+ scattering where the interaction mechanism is quite different. In the case of CO2, vibrational excitation in forward scattering is caused primarily by the long-range dipole interaction. The spectra are very similar for H−-CO2 and H+-CO2. Finer details are attributed to the influence of transient charge transfer and valence interactions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01411930
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