Electronic states of the FeF molecule. I. Analysis of rotational structure

The Ultraviolet Spectrum of the FeF Radical: A Study of the 6Π–X6Δ and 6Φ–X6Δ Band Systems at 330 and 323 nm Respectively

“…The PMT signal was used as the input for a lock-in amplifier. The monochromator was used as a variable bandpass filter by detecting fluorescence to the v = 1 level of the X 6 state, the frequency of which can be found using the vibrational parameters provided by Pouilly et al (15). This reduced the noise from scattered laser light and hence improved the signal-to-noise ratio of the experiment.…”

“…The dashed line represents the subband observed in Ref. (15), which was included in the fit. and so only a few lines could be measured in regions of the spectra where the 6 -X 6 lines were absent.…”

“…Hence it was possible to fit the (0,0) and (1,0) bands of the 6 -X 6 , the (0,0) band of the 6 -X 6 , and the millimeter-wave data for the v = 0 level (18) of the X 6 state together simultaneously. Additional data from the work by Pouilly et al (15,31) were also added. This included data on the 6 1/2 -X 6 −1/2 subband not recorded in our work and extension of the 6 7/2 -X 6 9/2 and 6 5/2 -X 6 7/2 sub-bands and 30897.27(2) cm −1 for the 6 1/2 -X 6 −1/2 sub-band, where the numbers in parentheses represent 3σ .…”

“…Rotationally resolved spectra were recorded by Pouilly et al (15) in absorption using a King furnace and in emission from hollow cathode discharges. Rotational analyses were performed on two systems in the ultraviolet region.…”

“…In this work, we have looked at the same band systems, at 330 and 323 nm, as Pouilly et al (15) by laser-induced fluorescence but with FeF produced at near-ambient temperature and studied under higher resolution. This has allowed us to extend the observations considerably compared with the previous work on these systems.…”