State-to-state studies of ground state NH(X 3Σ−,v=0,J,N)+Ne

Abstract

State-to-state rotational energy transfer of ground state NH(X 3Σ,v=0,J,N) in collisions with Ne is examined. NH is exclusively generated in the metastable NH(a 1Δ) state via photodissociation of hydrazoic acid at a wavelength of 266 nm. The strongly forbidden NH(a 1Δ→X 3Σ−) intercombination transition around 794 nm is used to generate single state NH(X 3Σ−,v=0,J,N) applying the stimulated emission pumping technique. The ground state radicals are detected after a certain delay time with laser induced fluorescence (LIF) using the intense NH(A 3Π←X 3Σ−) transition around 336 nm with respect to all quantum states. The collision induced energy flux between the different rotation and spin levels is studied in detail and a comprehensive set of state-to-state rate constants for inelastic collisions of NH(X 3Σ−,v=0,J,N) with Ne up to N=7 which include the effect of multiple collisions is given. The state-to-state rate constants are obtained by the use of an iterative integrated profiles method. We find a propensity for (ΔN=0, Δi=±1) and (ΔN=±1, Δi=0) transitions where N represents the quantum state for nuclear rotation and i represents the index of the spin component Fi. In most cases the energy transfer which changes the spin component and conserves the nuclear rotation quantum number N (ΔN=0, Δi=±1), is the most effective energy transfer in collisions with Ne. The energy dependence of the transition efficiency concerning only the nuclear rotation quantum number N obeys an energy-gap law (EGL).