DETECTION OF COLD SPECTRA FROM A ROOM-TEMPERATURE ENSEMBLE - MAGNETICROTATION SPECTROSCOPY WITH SIMPLE INTERPRETATION IN TERMS OF MOLECULAR PENDULAR STATES

The anisotropic orientation of the figure axis of pendular molecules i s directly detected by polarization spectroscopy for IC1 in the excite d A (3) Pi(1) state. A simple geometric model is outlined that simulat es all spectral features over a wide range of experimental parameters, without any fitting procedure. The experimental technique, closely re lated to magnetic rotation spectroscopy, strongly favors low rotationa l states and is also selective for Delta J within a rotational band. S pectra obtained using a gas cell at room temperature thereby become ev en sparser and simpler than can be attained by cooling molecules to a few kelvin. Moreover, it provides a technique for local measurement of electric or magnetic field strengths without mechanical devices.