Focusing of a cold PbO molecular beam with a superconducting microwave resonator

Focusing of a molecular beam in a high-field seeking state by an intense microwave standing wave is demonstrated. An 18 GHz microwave field that is near resonant to a rotational transition deflects a molecular beam due to the first-order ac Stark shift. The intense standing wave is obtained with a 47 cm long superconducting microwave resonator with a high unloaded quality factor of about 10 ⁶ . A cold molecular beam of PbO in the rotational ground state with a center velocity of 145 ms ^-1 is efficiently focused to have about a factor 10 enhancement of the flux density by the resonator with a microwave input power of about 1 W, despite the heaviness of the PbO molecule.