The Infrared Spectra of the NH3-dn+ Cations Trapped in Solid Neon

Published

March 1, 2001

Author(s)

Warren E. Thompson, Marilyn E. Jacox

Abstract

When a dilute mixture of NH₃ in neon is subjected to Penning ionization and/or photoionization by neon atoms in their first excited states, between 16.6 eV and 16.85 eV, and the products are rapidly frozen at approximately 5 K, the infrared spectrum of the resulting deposit includes three relatively prominent product absorptions which agree well with the positions determined in earlier gas-phase studies for the three infrared-active fundamentals of ¹⁴NH₃⁺. The corresponding fundamentals of ¹⁵NH₃⁺, ¹⁴ND₃⁺, and ¹⁵ND₃⁺ have been observed as have been many of the fundamentals of the partially deuterium-substituted cations, in experiments on isotopically enriched NH₃ samples. When the effects of anharmonicity are considered (including the occurrence of negative anharmonicity for the out-of-plane deformation fundamental), the positions of these absorptions agree satisfactorily with those predicted in an earlier study from the fit of an ab initio potential surface to the experimental data for ¹⁴NH₃⁺, as well as with those predicted in the present study from a least-squares force constant adjustment to the frequencies observed for the various isotopomers.

Citation

Journal of Chemical Physics

Volume

114

Issue

No. 11

Pub Type

Journals

Keywords

infrared spectrum, ND3⁺, neon matrix, NH₂D⁺, NH₃⁺, NHD₂⁺, normal coordinate analysis, photoionization

Citation

Thompson, W. and Jacox, M. (2001), The Infrared Spectra of the NH₃-d_n⁺ Cations Trapped in Solid Neon, Journal of Chemical Physics (Accessed July 27, 2024)