Precision Spectroscopy of Tellurium

Tellurium (Te$_2$) is widely used as a frequency reference, and although a standard atlas encompassing over 5200~cm$^{-1}$ already exists [1], Doppler broadening present in that work buries a significant portion of the features. More recent but less complete studies of Te$_2$ exist which do not exhibit Doppler broadening [2-4], and this work adds to that knowledge a few hundred transitions in the vicinity of 444~nm. Using a Fabry Perot cavity in a shock-absorbing, temperature and pressure regulated chamber, locked to a Zeeman stabilized HeNe laser, we measure changes in frequency of our diode laser to $\sim$1~MHz precision. This diode laser is scanned over 1000 GHz for use in a saturated-absorption spectroscopy cell filled with Te$_2$ vapor. This data allows for new studies of the excited states of Te$_2$.\\[4pt] [1] J.~Cariou, and P.~Luc, Atlas du spectre d'absorption de la molecule de tellure, Laboratoire Aime-Cotton (1980).\\[0pt] [2] J.~Verges et~al., Physica Scripta {\bf 25}, 338 (1982).\\[0pt] [3] Ph.~Courteille et~al., Appl. Phys. B {\bf 59}, 187 (1994)\\[0pt] [4] T.J.~Scholl et~al., J. Opt. Soc. Am. B {\bf 22}, 1128 (2005).