High resolution spectroscopy of B0←X0 transitions in Te: Reference lines spanning the 443.2-451.4 nm region.

Molecular tellurium (Te) has long been regarded as a promising candidate for a variety of spectroscopic applications, especially as a frequency reference. Absorption lines of Te were published extensively in the past few decades, however, the spectral resolution was not sufficiently high to be considered a precision spectroscopic reference. Here, a high resolution spectral atlas of Te Doppler-free saturated absorption transitions is reported, and used to assign multiple ro-vibrational bands in the B(Σu-3)0←X(Σu-3)0 electronic transition via the Dunham model, giving updated Dunham parameters and diatomic constants for the B(Σu-3)0 state at an unprecedented level of precision. Our findings reveal spectroscopic properties of Te that might eventually contribute to frequency reference in precision measurement such as the quest for non-zero electron's Electric Dipole Moment (eEDM).