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Abstract

Colliding a beam of metastable Kr atoms with an N₂ gas target, the resulting N₂(B ³Π_g --> A ³Σ_u⁺) emission was observed with a spectral resolution of up to 0.15 nm fwhm. Optical multichannel detection was employed, using a cooled diode array detector. This allowed the first rotationally well- resolved product emission spectra from the Kr*+N₂ reaction to be obtained. Also, the beam energy was varied between 69 and 191 meV(CM) by seeding with H₂. The rovibrational product distributions were derived from spectral simulations. In agreement with the literature, nonresonant (exothermic) E-E transfer was observed, populating the vibrational levels N₂(B,ν'=4-12). This broad distribution was found to be essentially independent of the collision energy. The product rotation could be well described by Boltzmann distributions with T_rot = 1300-1050 K for ν' = 5-12 at low and 1750-1400 K at high collision energy. A discussion of the reaction mechanism is given in terms of two alternative models, involving either an intermediate ion pair formation or a direct covalent curve crossing. Comparisons are made with the related reactions of Ar and Xe metastables.