Electronic Spectroscopy of SmO in the 645 to 670 nm Range

Abstract

The associative ionization reaction Sm + O → SmO+ + e – is being investigated as an electron source that could transiently modify high-altitude electron densities via Sm vapor release. Electronic spectra have been obtained from tests where sounding rockets released Sm vapor, but the interpretation of these results has been hampered by the limited laboratory spectral data available for both SmO and SmO+. The present study extends the spectroscopic characterization of SmO in the 645–670 nm range, where the field data show the most prominent molecular emission features. Rotationally resolved excitation spectra, dispersed laser-induced fluorescence spectra, and fluorescence decay lifetimes are reported. The results are consistent with the assignment of a subset of the red-region bands to configurational transitions of the form Sm2+(4f 5 6s)­O2– ↔ Sm2+(4f55d)­O2–. Analysis of the excited state hyperfine structure supports this configurational description.

Electronic Spectroscopy of Jet-Cooled NdO

“…The short radiative lifetimes observed in this study (30–150 ns), combined with the near vertical Franck–Condon factor intensity distributions of the DLIF spectra, indicate that the electronic transitions shown in Figure were strongly allowed. The range of lifetimes was similar to the values for SmO that we found in our recent study …”

“…In recent work on the spectroscopy of SmO, we found that the excitation of jet-cooled SmO using 193 nm light from an excimer laser produced an emission spectrum that was remarkably similar to the spectra recorded in the MOSC experiments, and the chemiluminescent reactions of Sm with oxidants O 3 , N 2 O, NO 2 , and SO 2 . Consequently, we examined the emission spectra generated by exciting NdO using 193 and 248 nm light (ArF and KrF lasers).…”

“…The range of lifetimes was similar to the values for SmO that we found in our recent study. 17 In total, nine new electronically excited states of NdO have been observed in this study, and a few linkages between these states can be identified. The transitions at 18075.39 and 17601.76 cm −1 (553.24 and 568.13 nm) terminate on a common upper state.…”

“…Analysis of the spectroscopic data from the Sm MOSC experiments has been facilitated by the availability of laboratory data for the electronic transitions of Sm and SmO. , Recent work shows that the MOSC red-bands of SmO coincide with strongly allowed, high fluorescent quantum yield transitions observed using laser induced fluorescence (LIF) and slow electron velocity map imaging (SEVI) techniques. , As summarized below, there have been several spectroscopic studies of NdO. − However, those investigations primarily focused on bands occurring in the red and far-red spectral ranges. The data for the green spectral range are sparse.…”