CALCULATIONS AND FIRST QUANTITATIVE LABORATORY MEASUREMENTS OF O$_{2}$ $A$-BAND ELECTRIC QUADRUPOLE LINE INTENSITIES AND POSITIONS

Abstract

Frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) was utilized to make quantitative laboratory-based measurements of electric quadrupole transitions within the $^{16}$O$_{2}$ $\textit{A}$-band. We report the first observations of eight extremely weak (line intensities ranging from 3x$10^{-30}$ to 2x$10^{-29}$ cm molec.$^{-1}$) transitions within the $\textit{ NO}$, $\textit{ PO}$, and $\textit{ RS}$ branches. New theoretical calculations of line intensities and positions are also presented and compared to these measurements. \begin{wrapfigure}[9]{i}{10.5cm} \vspace{-0cm} \hspace*{-0cm} \epsfig{file=OSU_Quad_Abstract222.eps} \end{wrapfigure} $\newline$ $\mathbf{Left}$: Measured spectrum (symbols) and Voigt fit (line) of electric quadrupole line in the wings of the $PQ$(11) hot band, magnetic dipole line. Peak signal-to-noise ratio on electric quadrupole line is 16:1. $\mathbf{Right}$: Fit-derived peak areas vs. number density for the $NO$ branch electric quadrupole lines.