When a Ne:PF5 or a Ne:PF3 mixture is codeposited at 5 K with a beam of neon atoms that have been excited in a microwave discharge, the infrared spectrum of the resulting solid shows a complicated pattern of new absorptions. Little fragmentation of PF5 into PF3 occurs, but several of the absorptions can be tentatively attributed to PF4. The results of extensive ab initio calculations of the vibrational spectra of the neutral, cation, and anion species of formula PFn are presented, in order to aid in the product identification. Several absorptions of PF4+, PF3+, and PF2+ are identified, with only PF3+ common to both systems. Other prominent absorptions are contributed by PF5-, PF4-, and PF3-. In all of the Ne:PF5 experiments and some of the Ne:PF3 experiments, F3PO was a major contaminant. Therefore, ab initio calculations were also conducted for most of the neutral and charged species that can result from F3PO. There is strong evidence supporting the identification of two of the vibrational fundamentals of F3PO-, and some evidence for a third. Tentative assignments are suggested for neutral and other charged species derived from F3PO. [S0021-9606(98)03320-0]