Dispersed fluorescence spectroscopy of the CBr₂ Ã ¹B₁-X̃ ¹A₁ transition

Dispersed fluorescence spectra following the excitation of the CBr ₂ Ã ¹B₁X̃ ¹A₁ 2₀¹³ and 2₀¹⁴ bands at visible wavelengths were acquired in a discharge supersonic free jet expansion using an intensified charge-coupled device (ICCD) detector. The dispersed fluorescence spectra show signal-to-noise ratios of up to 60 and extend out to a maximum red shift frequency of 6000 cm^-1. Complete and detailed vibrational structure of the ground singlet state (X̃ ¹A₁) was observed. Vibrational parameters including fundamental frequencies, anharmonicities, and coupling constants were determined for the CBr₂ X̃ ¹A₁ state. Additional vibrational structure starting at approximately 3650 cm^-1 was observed and this indicates the singlet-triplet energy gap to be > 10 kcal mol^-1.