High resolution spectroscopy on Te_2: new lines for reference

TL;DR

This paper reports high-resolution spectroscopy of tellurium near 455 nm, discovering over 100 new spectral lines suitable for laser frequency standards, filling a gap in existing spectral data.

Contribution

The study provides new high-resolution spectral lines of tellurium near 455 nm, expanding the spectral atlas for precision laser applications.

Findings

Over 100 new spectral lines identified

Spectral resolution of a few MHz achieved

Lines suitable for laser frequency locking

Abstract

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.