Single vibronic level emission spectroscopy of the system of dibromocarbene

Single vibronic level emission spectroscopy of the system of bromochlorocarbene

“…Compared with other related halocarbenes such as CBr 2 [49], the agreement with theory is poorer in this case; in particular, the symmetric stretching frequency is significantly underestimated by theory. Such a discrepancy could be caused by coupling among the stretching states; however, we have no evidence for such mixing from our emission spectra.…”

“…In the region between $3500 and 9000 cm À1 above the vibrationless level of the e X 1 A 1 state, we found only a very modest increase in ðA 00 À B 00 Þ, and $86% of the lines observed between 5000 and 9000 cm À1 could be assigned to e X 1 A 1 levels within 3 standard deviations of our Dunham expansion fit, which included more than 140 levels in total. Following the development of an improved discharge recipe for the clean production of CBr 2 , we subsequently reported SVL emission spectra of C 79 Br 81 Br and C 81 Br 2 which probed the vibrational structure of the e X 1 A 1 state up to $7000 cm À1 above the vibrationless level [49]. These spectra revealed many previously unassigned levels, and a nearly complete set of vibrational parameters was determined, which were in good agreement with ab initio predictions [49].…”

“…Such a discrepancy could be caused by coupling among the stretching states; however, we have no evidence for such mixing from our emission spectra. Our initial goal in measuring SVL emission spectra of CBrCl was to search for the presence of triplet levels using K a -sorted emission spectroscopy, [49] a method we have previously applied to CHCl and C 35 Cl 2 . In beginning this work, we anticipated that CBrCl would be a good system for the application of this method; however, the very weak signal in the high energy region precluded the measurement of lines near the predicted position of the triplet origin ($6000-6600 cm À1 ) [31,39,57].…”

“…Following the development of an improved discharge recipe for the clean production of CBr 2 , we subsequently reported SVL emission spectra of C 79 Br 81 Br and C 81 Br 2 which probed the vibrational structure of the e X 1 A 1 state up to $7000 cm À1 above the vibrationless level [49]. These spectra revealed many previously unassigned levels, and a nearly complete set of vibrational parameters was determined, which were in good agreement with ab initio predictions [49]. In this work no evidence was found for perturbations due to the low-lying triplet state, although analysis of the spectra was complicated by a polyad structure arising from the near 3:1 resonance of bending and symmetric stretching frequencies.…”

Electronic spectroscopy, lifetimes, and barrier to linearity in the system of dibromocarbene

“…Following the development of an improved discharge recipe for production of this carbene largely free from interference of CHBr or Br 2 , we have recently recorded and rotationally analyzed the complete visible fluorescence excitation spectrum of CBr 2 , which led to a revision in the assignment of the electronic origin of this system [29]. We have also measured extensive single vibronic level emission spectra of this system, in order to probe for spin-orbit interactions and the singlet-triplet gap [30]. In this report, we present the complete results of our analysis of thẽ A 1 B 1 X 1 A 1 system, focusing on the excited state structure and barrier to linearity.…”