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Protons solvated in noble-gas matrices: interaction with nitrogen.
Antti Lignell1, Leonid Khriachtchev, Hanna Lignell
1Laboratory of Physical Chemistry, University of Helsinki, Finland. lignell@csc.fi
Physical Chemistry Chemical Physics : PCCP
|May 25, 2006
Summary
Noble gas dimer cations interacting with nitrogen were computationally studied. Experimental results suggest a single complex structure, though discrepancies with theory highlight matrix effects on proton mobility and cation decay mechanisms.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Noble gas dimer cations are model systems for studying ion-molecule interactions.
- Understanding these interactions is crucial for ion chemistry in condensed phases.
Purpose of the Study:
- To computationally investigate the structure, energetics, and vibrational properties of (NgHNg)(+)–N2 complexes (Ng = Ar, Kr).
- To experimentally characterize these complexes using IR absorption spectroscopy in noble gas matrices.
- To elucidate the cation decay mechanisms in noble gas matrices.
Main Methods:
- *Ab initio* calculations at the MP2/6-311++G(2d,2p) level of theory.
- Infrared (IR) absorption spectroscopy in solid argon and krypton matrices.
- Analysis of vibrational frequencies and band shapes.
Main Results:
- Two stable structures (linear and T-shaped) were computationally identified with significant binding energies.
- Experimental IR spectra indicated the presence of only one complex structure, with a single nitrogen-induced band.
- Discrepancies between computational predictions and experimental observations suggest matrix effects influence complex stability.
- Similar cation decay rates for the complex and the bare cation imply proton immobility.
Conclusions:
- The interaction of noble gas dimer cations with nitrogen leads to stable complexes.
- Matrix isolation experiments reveal complexities in accurately modeling these systems due to environmental influences.
- Proton tunneling is hindered in noble gas matrices, and cation decay likely proceeds via electron neutralization.