The reaction of F atoms with CO in an argon matrix. Vibrational and electronic spectra of FCO

Upon codeposition at 14 K of an Ar:CO sample with an Ar:NF₃ sample that had been passed through a low-power microwave discharge in an Al₂O₃ tube, very prominent infrared absorptions of FCO and F₂CO were observed. Overtone bands of FCO were identified at 2032 and 3690 cm⁻¹, and their assignment was confirmed by both carbon-13 and oxygen-18 isotopic substitution. Further data were also obtained on the vibrational fundamentals of isotopically substituted F₂CO. A six-constant valence force potential has been derived for FCO using a least-squares force constant adjustment to the isotopic data and assuming a recently calculated structure. The photodissociation of FCO into F + CO was observed with a threshold near 2800 Å. The assignment of two overlapping electronic transitions of FCO between 3400 and 2300 Å is discussed.