Detection of Cold Spectra from a Room-Temperature Ensemble: Magnetic Rotation Spectroscopy with Simple Interpretation in Terms of Molecular Pendular States

Abstract

The anisotropic orientation of the figure axis of pendular mols. is directly detected by polarization spectroscopy for ICl in the excited A 3P1 state. A simple geometric model is outlined that simulates all spectral features over a wide range of exptl. parameters, without any fitting procedure. The exptl. technique, closely related to magnetic rotation spectroscopy, strongly favors low rotational states and is also selective for DJ within a rotational band. Spectra obtained using a gas cell at room temp. thereby become even sparser and simpler than can be attained by cooling mols. to a few kelvin. It provides a technique for local measurement of elec. or magnetic field strengths without mech. devices.