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Abstract:
Colliding a beam of metastable Kr atoms with an N2 gas target, the resulting N2(B 3Πg --> A 3Σu+) 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 Trot = 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.