The Four Isotopomer Reactions of NH(a) and ND(a) with NH3(X̃) and ND3(X̃)
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L. Adam
Abstract
The reactions
NH(a) + NH3(X̃) → products (1)
ND(a) + NH3(X̃) → products (2)
NH(a) + ND3(X̃) → products (3)
ND(a) + ND3(X̃) → products (4)
were studied in a quasi-static reaction cell at room temperature and pressures of 10 and 20mbar with He as the main carrier gas. The electronically excited reactants NH(a) and ND(a) were generated by laser-flash photolysis of HN3 and DN3, respectively, at λ = 308nm and detected by laser-induced fluorescence (LIF). Also the ground state species NH(X) and ND(X) as products were detected by LIF.
From the measured concentration-time profiles of NH(a) and ND(a) under pseudo-first order conditions, the following rate constants were obtained:
NH(a) + NH3(X̃) → products (1)
ND(a) + NH3(X̃) → products (2)
NH(a) + ND3(X̃) → products (3)
ND(a) + ND3(X̃) → products (4)
k1 = (9.1 ± 0.9) × 1013 cm3mol−1s−1
k2 = (9.6 ± 1.0) × 1013 cm3mol−1s−1
k3 = (8.0 ± 1.0) × 1013 cm3mol−1s−1
k4 = (7.2 ± 0.8) × 1013 cm3mol−1s−1.
The major products are the corresponding NHiD2 − i(X̃) radicals (i = 0, 1, 2), whereas quenching processes such as NH(a) + ND3 → NH(X) + ND3 are of minor importance (1%). The isotope exchange NH(a) + ND3 → ND(X) + NHD2 is negligible, and the corresponding channel on the singlet surface NH(a) + ND3(X~) → ND(a) + NHD2(X̃) contributes with 1% to the overall NH(a) depletion in that reaction. The experimental findings are discussed in terms of a chemical activation mechanism by means of statistical rate theory.
© 2004 Oldenbourg Wissenschaftsverlag GmbH
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Articles in the same Issue
- Preface – Prof. Dr. Klaus Scherzer on the occasion of his 70th birthday
- Cationic Van-der-Waals Complexes: Theoretical Study of Ar2H+ Structure and Stability
- Reaction of O(3P) Atoms with Benzene
- Towards the “Pressure and Materials Gap”: Hydrogenation of Acrolein Using Silver Catalysts
- Aggregation of 1-Palmitoyl-2-Oleoyl-Sn-Glycero-3-Phosphocholine in Nonaqueous Solutions Studied by Spectroscopic and Kinetic Probe Molecules and Dynamic Light Scattering
- The Four Isotopomer Reactions of NH(a) and ND(a) with NH3(X̃) and ND3(X̃)
- Limitations of Variational Transition State Theory for Barrierless Radical–Radical Recombination Reactions
- A Kinetic Study of the Reaction between the 2-Ċ3H7 Radical and i-C4H8: Enthalpy of Formation of the (CH3)2CHCH2Ċ(CH3)2 Radical
- Direct Kinetic Study of Reactions of Hydroxyl Radicals with Alkyl Formates
- Gas-Phase Kinetics of the Reactions of the CH2F Radicals with the Radicals CHF2, CH3, and C2H5
