Observation of dissociative and radiative states of N2H by neutralized ion beam techniques

Abstract

Neutralized ionbeam studies of the rare gas hydrides: Observation of unique metastability for NeH J. Chem. Phys. 88, 3116 (1988); 10.1063/1.453955 Observation and characterization of the CH5 radical by neutralized ion beam techniques J. Chem. Phys. 87, 5804 (1987); 10.1063/1.453504 The n=2,3 triplet Rydberg states of the HD molecule observed by fast neutralbeam photofragment spectroscopy J. Chem. Phys. 86, 3050 (1987); 10.1063/1.452010 Experimental observations of excited dissociative and metastable states of H3 in neutralized ion beamsThe N 2 H(D) radical has been studied experimentally by measurement ofthe kinetic energy release in its unimolecular dissociation following formation by electron transfer from metal atoms to high velocity, mass-resolved ion beams and theoretically by ab initio techniques. Calculations ofthe dissociation coordinate of the ground state radical at the MP4/6-311G*"'1 I MP3/6-311G*'" level of theory indicate that the radical is unstable with respect to N2 and H by 0.6 eV but separated from the dissociation products by a 0.4 eV Qarrier. One dimensional tunneling lifetimes are determined to be 7.0X 10-12 s for N2H and 3.6X 10-10 s for N2D.Neutralization of the ion by Zn targets produces predominantly radicals in the 2A I ground state with dissociative lifetimes 1" < 0.5 its, in agreement with the calculations. Mg targets produce the radical in a mixture of the 2 A I ground and 2 A "( 'IT) excited states with a branching ratio dependent on the internal energy of the precursor ion. A higher excited state of the radical, suggested to be an n = 3 Rydberg level, is produced with K targets and is inferred to undergo radiative transitions, probably containing some discrete structure, to the lower 2A I and 2A " ( 'IT) states in the wavelength range of 2700-4500 A. Observations of these transitions may constitute the first spectroscopic observation of the radical.

Nitrogen Adsorption and Hydrogenation on aMoFe6S9Complex

“…3). This is in contrast to the hydrogenation of gas phase N 2 , where the addition of an H atom is thermoneutral or endothermic [14]. This shows an important role of the MoFe 6 S 9 complex in activating the N 2 bond in analogy to other metal complexes [15].…”

Theoretical investigation of the potential energy surface for the NH2+NO reaction via density functional theory and ab initio molecular electronic structure theory

“…species as estimated theoretically 57,58 and experimentally. 59 Therefore, further energy calculations for ⌬H (1) 0 were also carried out at various levels of theory for comparison. The results are listed in Table IV.…”

The role of NNH in NO formation and control

“…NNH is a free radical that dissociates exothermically into N 2 + H by tunneling through a small (<8 kcal/mole) potential energy barrier. The lifetime of NNH has been inferred from experiment to have an upper limit of 0.5 µsec [25], but theoretical work (see [26] and discussion below) indicates values of 10 -8 -10 -11 s. Such a short lifetime implies that the N 2 + H recombination reaction is fast enough to maintain a partial equilibrium with NNH at combustion conditions. A subsequent reaction NNH + O = NH + NO then offers a high temperature pathway for NO formation, the so-called NNH mechanism.…”