Stark deceleration of OH radicals in low-field-seeking and high-field-seeking quantum states

TL;DR

This paper demonstrates the Stark deceleration of OH radicals in both low-field-seeking and high-field-seeking quantum states using an alternating-gradient method, achieving significant kinetic energy reduction and state control.

Contribution

It introduces a single setup capable of decelerating OH radicals in different quantum states with optimized switching sequences and independent control of molecular focusing.

Findings

Decelerated OH radicals from 345 m/s to 239 m/s in low-field-seeking state.

Decelerated OH radicals from 355 m/s to 316 m/s in high-field-seeking state.

Controlled hyperfine level crossing at 640 V/cm.

Abstract

The Stark deceleration of OH radicals in both low-field-seeking and high-field-seeking levels of the rovibronic ${}^2\Pi_{3/2},v=0,J=3/2$ ground state is demonstrated using a single experimental setup. Applying alternating-gradient focusing, OH radicals in their low-field-seeking ${}^2\Pi_{3/2},v=0,J=3/2,f$ state have been decelerated from 345 m/s to 239 m/s, removing 50 % of the kinetic energy using only 27 deceleration stages. The alternating-gradient decelerator allows to independently control longitudinal and transverse manipulation of the molecules. Optimized high-voltage switching sequences for the alternating-gradient deceleration are applied, in order to adjust the dynamic focusing strength in every deceleration stage to the changing velocity over the deceleration process. In addition we have also decelerated OH radicals in their high-field-seeking ${}^2\Pi_{3/2},v=0,J=3/2,e$ state from 355 m/s to 316 m/s. For the states involved, a real crossing of hyperfine levels occurs at 640 V/cm, which is examined by varying a bias voltage applied to the electrodes.