Semi-classical study of the molecular dissociation: H2 + He

Accurate vibrational wave functions and a state-dependent model interaction potential were used in the study, within the framework of a semi-classical theory, of the vibrational excitation and dissociation of the hydrogen molecule in collinear collisions with the helium atom. A molecule initially in the excited state is shown to be very efficient in energy transfer and twice more likely to be further excited than to be de-excited. The change in the population distribution among the vibrational states at the first few collisions was analyzed. It is shown that the population of the first vibrational excited state ψ₁ reaches its maximum after the very first collision and that of ψ₂ after the second. It is also found that at a sufficiently high collision energy, ψ₅ is the most efficient state in dissociation at the second collision while ψ₆ contributes most at the third collision.