Knowledge Bank

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. Theresults of earlier ab initio studies, as well as those of the present experimental and an initio studies, indicate that the $NeHF+$ complex is quite strongly bound. The $\nu 3$ absorptions of $NeHF-$ and $NeDF+$ are identified, and the $\nu 1+\nu 3$ absorption of $NeHF+$ is tentatively identified. An absorption at $3064.7cm-1$ has isotopic substitution behavior appropriate for its assignment to $HFFH+$. Density functional and more elaborate ab initio calculations support this assignment.