Laser-induced fluorescence and discharge emission spectra of CrO. Rotational analysis of the A⁵Π–X⁵Π transition

Abstract

The A5Π–X5Π electronic transition of CrO, near 6000 Å, has been analysed in detail using laser-induced fluorescence and conventional discharge emission spectroscopy. The transition provides the first instance where it has been possible to analyse the rotational structures of quintet electronic states completely. Although the parallel polarization of the transition has prevented the spin–orbit coupling and Λ-doubling intervals from being observed directly, it is shown that sufficient indirect information exists in the spectrum for them to be obtained with fair precision. The excited state, A5Π, is perturbed by large numbers of other electronic states which have no intensity of their own for emission to the ground state. The analysis of the perturbed regions has been greatly facilitated by the laser-induced fluorescence spectra: the excitation spectra correspond to a rotational temperature close to room temperature (which offers a significant improvement in resolution over the discharge spectra), and the J-assignments of the perturbed lines given by the resolved fluorescence spectra are unambigious

V4332 Sagittarii: a circumstellar disc obscuring the main object

“…(e) Wavelengths of the band heads derived from spectroscopic constants of Hocking et al (1980): 6451.953 (R 2 ), 6455.191 (R 3 ), 6459.463 (R 4 ), 6465.369 (R 5 ).…”

“…(1) see references in Kamiński et al (2009); (2) Rosen (1970); (3) Schwenke (1998); (4) Phillips (1973); (5) Hocking et al (1980). corresponds to V LSR = 6.5 km s −1 .…”

Depletion Kinetics of the Ground State CrO Generated from the Reaction of Unsaturated Cr(CO)xwith O2and N2O

“…However, they are somewhat longer than those from recently reported by Hedgecock et al 21 Hedgecock and coworkers obtained the radiative lifetimes under collisionless condition, whereas our values are obtained under multiple collision conditions. Because of the small energy difference (~55 cm Π Ω ), 9 the longer lifetimes in this work might be ascribed to the efficient collisional mixing among the different substates of CrO (B 5 Π Ω ). 22 The …”

“…7 Since the pioneering work of Ninomiya, 8 who analyzed a partially resolved rotational spectrum of the 600 nm band system of CrO, Merer and coworkers generated CrO molecules in the gas phase using a microwave discharge in flowing CrO 2 Cl 2 and He or using a microwave discharge through argon over solid CrO 3 , and analyzed rotational structures of the B Π transition bands. [9][10][11] Debore and Gole generated excited state CrO from the reaction of hot Cr atoms with O 3 and N 2 O, and assigned vibrational band structures of electronic transitions observed in their chemiluminescence spectra. 12 In our previous work, we have reported that the ground state FeO molecules can be easily generated in the gas phase by photolyzing a Fe(CO) 5 /O 2 or N 2 O/He mixture using unfocussed weak UV laser pulses at room temperature and highly unsaturated iron carbonyls are responsible for the formation of ground state FeO molecules.…”

“…Π Ω ) transition which was partially analyzed by Hocking et al 9 We have also investigated the effect of photolysis laser wavelength on the excitation spectrum of the CrO molecules. For this purpose, we have set the photolysis laser wavelength at 295.72 nm, which corresponds exactly to the Cr(z 3 D 4 à a 7 S 3 ) atomic transition frequency.…”