15min:

CATHERINE L. LUGEZ, MARILYN E. JACOX AND RUSSELL D. JOHNSON III, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441.

When a Ne:HF mixture 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 absorptions assigned to NeHF⁺ and HFFH⁺. Evidence is presented suggesting that neon-matrix shifts may be anomalously large for protonated molecules which are derived from species with proton affinities near or below 550 kJ/mol. The results of earlier ab initio studies, as well as those of the present experimental and ab initio studies, indicate that the NeHF⁺ complex is quite strongly bound. The ₃ absorptions of NeHF⁺ and NeDF⁺ are identified, and the ₁ + ₃ absorption of NeHF⁺ is tentatively identified. An absorption at 3064.7 cm^-1 has isotopic substitution behavior appropriate for its assignment to HFFH⁺. Density functional and more elaborate ab initio calculations support this assignment.