Knowledge Bank

Previously, we have reported low resolution fluorescence spectra of $C2$ and CN excited by the prism selected lines of $Ar+$ and $Kr+$ ion lasers in a $CH4/N2Oflame.1$ This paper reports higher resolution studies of these spectra. The $C2$ and CN are excited, as before, by placing the flame in the extended cavity of the ion laser. The fluorescence spectra are dispersed in a lm monochromator and detected with a vidicon (OMA I). Previously, we found that four of the available laser lines pump the $C2$ Swan system and eight pump the CN $B-Xsystem.1$ This higher resolution study allows assignment of most of the pumping transitions. All of the $C2$ pump transitions belong to the Swan system. Curiously, the 5145 {\AA} laser line pumps a different transition at high temperature than is observed at low $temperature.2$ CN may be pumped by either B-X or B-A transitions, depending upon the laser line selected. Several of the laser lines are found to pump more than one $C2$ or CN transition simultaneously, yielding complicated fluorescence spectra. Spectra from those lines which pump a single rotational transition yield information about the relative collisional energy transfer rates of the excited state radicals in the flame. Details of the pump transition assignments and energy transfer rates will be presented.