Knowledge Bank

The $\upsilon 1$ and $\upsilon 3$ fundamental bands of $NH2$ have been detected in absorption in the 2.9 to $3.2\mu m$ region using a difference frequency laser and a long path Zeeman-modulated discharge cell. The tunable infrared radiation was generated by mixing the output of an argon ion laser with that of a single-mode dye $laser1$. $NH2$ was produced by a, d, c, discharge in flowing $NH3$ at a pressure of about 0.8 Torr (106 Pa). About 100 vibration-rotation transitions have been measured and a simultaneous analysis of the Coriolis-coupled $\upsilon 1$ and $\upsilon 3$ states has been made. These results may prove useful in a search for interstellar $NH2$ by means of its vibration-rotation spectrum. While recording the spectrum of $NH2$, transitions belonging to the fundamental band of the NH radical were also observed. These results will be discussed.