Beam Study of the Luminescent E−E Energy Transfer Reaction Kr(³P₂) + N₂ → Kr + N₂(B ³Π_g) at High Resolution and Variable Collision Energy

Abstract

Colliding a beam of metastable Kr atoms with an N 2 gas target, the resulting N 2 (B 3 Π g f A 3 Σ 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* + N 2 reaction to be obtained. Also, the beam energy was varied between 69 and 191 meV CM by seeding with H 2 . 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 N 2 (B,V′)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 V′ ) 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. † Part of the special issue "Donald Setser Festschrift".

Gas temperature determination from rotational lines in non-equilibrium plasmas: a review

“…An important vibrational level dependence of the produced rotational level's density distribution has also been reported for the excitation transfer from Kr( 3 P 2 ) and Xe( 3 P 2 ) metastable atoms to nitrogen [44][45][46][47][48]. Energy transfer from Xe( 3 P 2 ) atoms selectively populates vibrational levels ν 5 of the N 2 (B) state.…”

“…However, the nascent rotational temperature of the less populated lower vibrational levels ν 4 can reach 3500 K [47]. Energy transfer from Kr( 3 P 2 ) metastable atoms also produces N 2 (B) molecules in vibrational levels up to ν = 12 [44,48]. Under room temperature conditions, the nascent rotational distributions correspond to rotational temperatures of about 1200 K [48].…”

“…Energy transfer from Kr( 3 P 2 ) metastable atoms also produces N 2 (B) molecules in vibrational levels up to ν = 12 [44,48]. Under room temperature conditions, the nascent rotational distributions correspond to rotational temperatures of about 1200 K [48]. Flowing afterglow experiments with argon and neon as carrier gas have shown [44] that the nascent rotational and vibrational distributions of N 2 (B) were less modified due to collisions with neon, as compared with argon as the collision partner.…”