Alignment and orientation for H(2p) excitation in ${\mathrm{H}}^{+}$-Ar collisions have been measured for incident proton energies of 1.5 and 3 keV, and in the range of scattering angles between 0.5° and 3.5°. From the experimental results the relative population of magnetic substates H(2$p_0$) and H(2$p_{\pm 1}$) is extracted. The observed magnitude of the H(2$p_0$) excitation suggests that, in addition to a 3dσ-3dπ rotational coupling, a 3dσ-4pσ radial coupling is effective.

• Received 27 July 1984

DOI:https://doi.org/10.1103/PhysRevA.31.1399