Semiclassical theory of resonant dissociative excitation of molecular ions by electron impact

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Atomic, molecular, and optical physics, 2020-10, Vol.53 (19), p.195201
• Main Authors: Narits, A A, Kislov, K S, Lebedev, V S
• Format: Article
• Language: English
• Subjects: dissociative excitation; electron impact; low-temperature plasmas; molecular ions; rare gases; resonant processes; Rydberg atoms
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/1361-6455/aba3a7

We have developed a semiclassical approach to the description of resonant dissociative excitation of a molecular ion induced by collisions with plasma free electrons and accompanied by the non-adiabatic transitions between its different electronic terms. It is based on the quasistatic treatment of nuclear particles relative motion in a molecular ion combined with the approximation of a quasicontinuum for rovibrational states. We have derived the semianalytic expressions for the Boltzmann-averaged cross sections, σ T de ( ε ) , and rate constants, α de(T, T e), of this process. The resulting expressions for σ T de ( ε ) and α de(T, T e) with explicit dependencies on the electron energy, ɛ, the gas, T, and electron, T e, temperatures are valid when the thermal energy k B T exceeds the value of the lowest vibrational quantum, ℏω e, of a molecular ion. The theory developed is applied to studying the resonant dissociative excitation of homo-nuclear H 2 + , A r 2 + and X e 2 + ions as well as the hetero-nuclear rare gas ions RgXe+ (Rg = Ne, Ar, and Kr) with significantly different values of the dissociation energy. The efficiencies of the electron-impact dissociative excitation process and dissociative recombination leading to the population of the Rydberg states are compared. Our results of calculations are in good agreement with the available experimental data.