AC Stark Effect Observed in a Microwave–Millimeter/Submillimeter Wave Double-Resonance Experiment

Abstract

Microwave-millimeter/submillimeter wave double-resonance spectroscopy has been developed with the use of technology typically employed in chirped pulse Fourier transform microwave spectroscopy and fast-sweep direct absorption (sub)millimeter-wave spectroscopy. This technique offers the high sensitivity provided by millimeter/submillimeter fast-sweep techniques with the rapid data acquisition offered by chirped pulse Fourier transform microwave spectrometers. Rather than detecting the movement of population as is observed in a traditional double-resonance experiment, instead we detected the splitting of spectral lines arising from the AC Stark effect. This new technique will prove invaluable when assigning complicated rotational spectra of complex molecules. The experimental design is presented along with the results from the double-resonance spectra of methanol as a proof-of-concept for this technique.

Experimental Observation of the Autler–Townes Splitting in Polyatomic Molecules

“…The dressed-atom approach that deals with the coupled system of atom and driving photons has been quite successful in explaining the experimental observation, providing the underlying physical insights. Actually, dressing the quantum state with the strong optical field is essential for the manipulation of atomic or molecular motions in terms of cooling, , trapping, or controlling chemical reactions. − Although the AT splitting is quite general, its experimental observation has been mostly confined to atoms, − artificial atoms, − or diatomic molecules. − For instance, AT splitting has never been reported for polyatomic molecular systems ( N > 3) in the electronic transition. In fact, AT splitting has not been anticipated for polyatomic molecules as obviously there are so many internal degrees of freedom that hamper the coherent Rabi oscillation.…”