ZEEMAN TUNING RATES IN THE $\nu_{3}$ BAND OF $NO_{2}$

Zeeman spectra of the $v_{3}$ fundamental (at $\\sim 1620 cm^{-1}$) of nitrogen dioxide $(^{14}NO_{2}$) have been recorded with magnetic fields of $\\sim 500$ Gauss using a FTS (at the Kitt Peak National Observatory), as well as a tunable diode laser. At low magnetic fields the Zeeman effect is small compared to the spin-rotation interaction, and the Zeeman tuning rates are expected to be linear with magnetic field. Measured tuning rates of the Q-branch ($K_{A} = 2-9, N = 2-16$)$\\sigma$ transitions are compared to those expected for $^{2}\\Sigma$ transitions in low magnetic fields, $\\sim 2\\mu_{o} gB/(2N+1)$. These measurements are required in the data analysis of an ultra-sensitive (pptv) {in situ} detector based on magnetic-rotation spectroscopy.