De-excitation of H(2p) in a collision with a H2 molecule

Abstract

The velocity assigned experiment of the collisional de‐excitation of a H(2p) atom by a H₂ molecule is demonstrated by measuring the time‐dependent intensity of Lyman‐α radiation emitted in the photodissociation of H₂ using a pulsed synchrotron radiation in the vacuum ultraviolet region. Observed decay rates of Lyman‐α radiation have given the rate constant or cross section for the de‐excitation of H(2p) by H₂. The cross section is about 3×10⁻¹⁴ cm² in the region of the collisional velocity between 4.6×10⁵ and 12×10⁵ cm/s, which is several times larger than that for the H(2s) de‐excitation. It has been concluded that the l‐changing collision is quite important in the de‐excitation of H(2p) by H₂.