Jet cooled laser-induced fluorescence spectroscopy of tantalum monocarbide: Observation of the ground state vibrations and the low-energy states

Abstract

• The equilibrium vibrational harmonic wavenumber, ω e for the ground state determined • Present ω e is more accurate and smaller by 28% from the earlier reported value • New assignments of the excitation bands • Low-energy excited states observed and tentatively assigned Laser-induced excitation and dispersed fluorescence (DF) spectra of TaC molecule, produced in laser vaporization free-jet apparatus, were studied to investigate the electronic structure. The DF from the earlier reported and newly assigned bands showed the ground state vibrational progression v = 0−3 and 5. Further, the observation and rotational analysis of the hot band from v = 1 of the ground state confirmed the T v = 1 = 769.108 ( 9 ) c m − 1 . The analysis of the vibrational and band origin data yielded the harmonic frequency ω e = 769.1(1) cm −1 for the X 2 Σ + ground electronic state. This value is distinctly different from the earlier reported value of 1064 cm −1 determined from the anion-photoelectron spectroscopy work (Phys. Rev. A 92 (2015) 042503). Additionally, the reasonably intense dispersed fluorescence peaks between the displacement wavenumber 2400 to 5900 cm −1 are tentatively assigned to low-lying states predicted by the earlier ab initio studies.