Knowledge Bank

Eighteen previously unobserved bands belonging to the BiF $AO+\to X1O+$ system have been identified in the region between 6550 and 7400 {\AA} using the technique of laser induced fluorescence. A pyrolytic beam source of Bi atoms was used to produce the product BiF in a reaction with molecular fluorine under single collision conditions. The measured spectrum extends to 6150 {\AA}, but because of the increasing number of transitions in this region the sequence pattern becomes unrecognizable under our experimental conditions. The bands identified at wavelengths longer than 6550 {\AA} compose the $\Delta v=-12$ to $\Delta v=-16$ sequences. The vibrational assignment follows from an extrapolation of the constants of Ross $etal.1$ Nine bands representing $v\prime -27-29$ and $v\prime \prime -40-45$ have been rotationally analyzed and the $v\prime -27$ and $v\prime -29$ states exhibit strong homogeneous perturbations. These bands are also observed to predissociate, providing evidence for an A O' state potential maximum which has been theoretically $predicted.2$ A limiting curve of dissociation suggests a rotationless potential maximum at $32672\pm 16cm-1$ with respect to the minimum of $X1O+$. This energy must correspond to a potential maximum if it is to be reconciled with recent thermochemical measurements of the ground state dissociation energy, $D0-3.76\pm 0.13eV.3$ The collision free lifetimes of selected A O+ rotational states are similar to those measured previously for lower states, except for longer values for strongly perturbed states, or shorter values for predissociated states. The vibrational and rotational analysis will be discussed.