DRESSED STATES OF MOLECULES AND MICROWAVE-INFRARED DOUBLE-RESONANCE SPECTROSCOPIC TECHNIQUES EMPLOYING AN ELECTRIC QUADRUPOLE FOCUSING FIELD

High-sensitivity, microwave-infrared double-resonance measurements can be made in molecular-beam spectrometers employing a single state-focu sing device. The key feature of the double-resonance technique is the achievement of large signal modulations of infrared signals using micr owave transitions, even in cases where the infrared transition cannot be saturated. A series of measurements is presented that shows that th e technique is based on the transition moment and state-focusing prope rties of dressed molecular states in the presence of a strong microwav e held. Using a state-focusing device, the spectroscopic measurements are doubly sensitive to the composition of the dressed states. The tec hnique can be extended to other types of spectroscopy, such as electro nic spectroscopy and the spectroscopy of weakly bound complexes. (C) 1 997 American Institute of Physics.