Knowledge Bank

In microwave optical double resonance spectroscopy (MODR) the primary interest is generally in the accurate measurement of the microwave adsorption frequencies. In the work described here though, known microwave transitional frequencies are pumped and the optical transitions frequency of the dye laser is swept. MODR signals are seen in both 3-level and 4-level (collisional) schemes. The method has been applied to $NH2$ on the $110,J-1/2,\Pi (0,10,0)\leftrightarrow u$ transition around $6.3CHz1$. Double resonance signals were observed for many known ortho levels in etc. Two levels (presumably) responsible for a perturbation to $110,\Pi (0,10,0),(F1andF2)$, were located. In the ``u'' manifold of states, $F1$ and $F2$ components of rotational levels with $N-2,Ka-2$ and $N-3,Ka-2$ were observed. Attempts at a vibronic assignment of the u manifold have so far been unsuccessful. Application of the method to other molecules may be described.