Rotational analysis of the HCO B˜(2A′)-X˜(2A′)311 and 321 bands

We report laser-induced fluorescence spectra of the B˜2A′-X˜2A′ transition of the formyl radical, HCO, produced by photolysis of jet-cooled formaldehyde. Two spectral regions were studied: from 38 615 to 38 712 cm−1, which corresponds to the overlapping 000 and 311 transitions, and from 37 535 to 37 640 cm−1, corresponding to the overlapping, and 310 and 321 transitions. Over 170 transitions in the 311 band and 80 transitions in the 321 band were assigned and fit using a non-linear least squares routine to provide rotational, centrifugal distortion and spin-rotation constants in the HCO X˜2A′(0,0,2) and B˜2A′(0,0,1) states.