THE OPTICAL SPECTRUM OF THE FELL RADICAL RECORDED AT AMBIENT TEMPERATURES

$^{1}$ J.G. Phillips, S.P. Davis, B. Lindgren and W.J. Balfour, Astrophys. J. Suppl., 65, 721 (1987) $^{2}$ P.K. Carroll, P. McCormack, and S. O'Connor, Astrophys. J., 208, 903 (1976)Author Institution: The physical Chemistry Laboratory, University of Oxford; The Department Of Chemistry, Arizona State UniversityThe electronic spectrum of FeH has been observed both in astrophysical sources and in the laboratory using a King furnace. The temperatures of both these sources are very high and the spectra obtained are very complicated. Despite this an analysis of the near infra-red bands, showing them to de due to $^{4}\Delta- ^{4}\Delta$ transition, has been $published.^{1}$ It now seems very likely that the lower $^{4}\Delta$ state of this transition is the ground state. We have recorded many rotational lines in the green (Around 530nm) and blue (around 490nm) systems by laser excitation, spectroscopy. The molecule was generated at near ambient temperatures by reaction of Fe(Co)$_{5}$ and H atoms. The measured wave numbers obtained are consistent with those previously obtained and are more accurate. The system is simpler however consistent with the lower sample temperature. As previously obtained and are more accurate. The system is simpler however, consistent with the lower sample temperature. As previously $reported^{2}$ both these systems have a many lined appearance with no apparent band structure, In order to help with analysis we have dispersed the fluourescence of some of the stronger lines in both systems. The results from this experiment imply that both the systems are due to perpendicular transitions, the green and blue systems obeying a $\Delta=-1$ and $+1$ selection rule respectively. It seems most likely that the two systems arise from the same lower state and that this state is not the ground state. In addition we have recorded a previously undetected system around 450nm which we have recently assigned to a $^{6}\Phi-^{4}\Delta$ transition. Resolving the fluorescence from system has allowed us to determine the energy separation between the a$^{6}\Delta$ and $X^{4}\Delta$ states. These results and others will be presented at the moeting