Rotational Energy Transfer within the $\tilde{A}$ $^{2}$A$_{1}$ State of NH$_{2}$: Absolute Rate Coefficients and the Influence of Spin Exchange in Collisions with H Atoms

摘要: Experiments are described which concern rotationally inelastic events occurring within the (0, 9, 0) vibronic level of $\tilde{A}$ $^{2}$A$\_{1}$ state NH$\_{2}$. Continuous-wave (c.w.) dye-laser excitation and dispersion resulting fluorescence allows observation specific rotational to processes. It is demonstrated experimentally that hydrogen atoms dominant agent in causing these events. Absolute rate coefficients for transfer quoted shown where relevant agree with principle microscopic reversibility. Propensity rules clearly evident, it found transitions $\Delta K=0 2$ occur very similar rates. The data interpreted terms restricted distorted-wave Born model. This model give a semi-quantitative fit experimental data. In order explain anomalies rates among levels para symmetry collisionally induced diabatic mechanism proposed high ground $\tilde{X}$ $^{2}$B$\_{1}$ NH$\_{2}$ involved. electronic spectrum possesses resolvable doublet structure. A series experiments relative populations populated spin doublets were measured. These results theory set out preceding paper (Dixon & Field 1978) encounters both collision partners open-shell. We show our findings point marked correlation interaction potential. allow us draw conclusions regarding anisotropy potential H analysis branching indicates strength triplet singlet surface be approximately ratio 1:4. Such consistent physical picture emerges from qualitative knowledge surfaces NH$_{3}$ system. general relevance laser modelling exchange interstellar maser action noted.