UV SPECTROSCOPY OF THE $B^{2}A'$ AND $C^{2}A'$ STATES OF FCO.

Abstract

Gas phase UV spectra of $FC^{16}O$ and $FC^{18}O$, produced by laser photolysis of $F_{2}$ in the presence of CO, are obtained in the region between 29000$cm^{-1}$ and $43000 cm^{-1}$(1). The three prominent progressions are assigned to the $B^{2}A^{\prime}$ and $C^{2}A^{\prime}$ states of FCO and a fourth, weaker progression may be belong to the second excited $^{2}A^{\prime}$ state. For the $B^{2}A^{\prime}$ sate, we obtained vibrational frequencies of $v_{1}=1120 \pm 40 cm^{-1}$ and $\nu_{2}=780 \pm 30 cm^{-1}$ and a zero point energy in the range $24000 < T_{0} < 27000 cm^{-1}$. The spectrum of the $C^{2}A^{\prime\prime}$ state yields $\nu_{1}=1458 \pm 6 cm^{-1}$ and $\nu_{2}=651 \pm 2 cm^{-1}$ and a zero point energy of $T_{0}=28500 \pm 25 cm^{-1}$. The electronic energies and frequencies are compared to recent {ab initio} calculations.