High resolution spectroscopy on Te₂: new lines for reference

Ro-vibrational spectra of different electronic states of molecules are often used as absolute wavelength or frequency standards. These standards are also used to mitigate any slow drift of laser frequency during an experiment. In precision experiment, the two most commonly used molecular standards are iodine and tellurium, both are homo-nuclear diatomic molecules. The former is mostly used as standard for the long wavelength ($600-900$~nm) region, while the tellurium spectrum is widely used in short wavelength ($400-550$~nm) including near ultra violet. A comprehensive data on tellurium spectra can be obtained from the tellurium atlas~\cite{Te2atlas:80}. However near the $455~$nm range where a number of important atomic resonance line, the atlas provides no significant data. We have performed high resolution modulation transfer spectroscopy~(MTS) on tellurium molecule in a hot cell in the region close to $455~$nm wavelength thereby obtained more than $100$ new spectral lines which were not observed before. The resolution of each of these peaks is about few MHz, making them suitable for laser frequency locking.