Production of cold formaldehyde molecules for study and control of chemical reaction dynamics with hydroxyl radicals

Hyperfine structure of the hydroxyl free radical (OH) in electric and magnetic fields

We investigate single-particle energy spectra of the hydroxyl free radical (OH) in the lowest electronic and rovibrational level under combined static electric and magnetic fields, as an example of heteronuclear polar diatomic molecules. In addition to the fine-structure interactions, the hyperfine interactions and centrifugal distortion effects are taken into account to yield the zero-field spectrum of the lowest ${}^2Π_{3/2}$ manifold to an accuracy of less than 2 kHz. We also examine level crossings and repulsions in the hyperfine structure induced by applied electric and magnetic fields. C…

Phase Space Manipulation of Cold Free Radical OH Molecules

We report bunching, slowing, and acceleration of a supersonically cooled beam of diatomic hydroxyl radicals (OH). \textit{In situ} observation of laser-induced fluorescence along the beam propagation path allows for detailed characterization of longitudinal phase-space manipulation of OH molecules through the Stark effect by precisely sequenced inhomogeneous electric fields.

正常强度分布律（NIDL）在羟基自由基振转发射光谱中的体现

Manifestation of the Normal Intensity Distribution Law (NIDL) in the rovibrational emission spectrum of hydroxyl radical

本研究用NIDL分析羟基自由基振转发射光谱的实验与理论数据，明确其适用边界，验证双原子氢化物的小约化质量效应，并通过从头算对比不同势能，提出光谱数据库计算可采用差异化势能的思路。

Cold free radical molecules in the laboratory frame

A special class of molecules that are important to many subfields in molecular dynamics and chemical physics, namely free radical molecules, now enjoy a significant degree of center-of-mass motion control in the laboratory frame. The example reported in this paper concerns hydroxyl radical (OH), which, after the internal degrees of freedom are cooled in a supersonic expansion, has been bunched, accelerated, and slowed using time-varying inhomogeneous electric fields. In situ observations of laser-induced fluorescence along the beam propagation path allows for detailed characterization of the l…

Evaporative cooling of the dipolar radical OH

Atomic physics was revolutionized by the development of forced evaporative cooling: it led directly to the observation of Bose-Einstein condensation, quantum-degenerate Fermi gases, and ultracold optical lattice simulations of condensed matter phenomena. More recently, great progress has been made in the production of cold molecular gases, whose permanent electric dipole moment is expected to generate rich, novel, and controllable phases, dynamics, and chemistry in these ultracold systems. However, while many strides have been made in both direct cooling and cold-association techniques, evapor…

Low-energy molecular collisions in a permanent magnetic trap

Cold, neutral hydroxyl radicals are Stark decelerated and confined within a magnetic trap consisting of two permanent ring magnets. The OH molecules are trapped in the ro-vibrational ground state at a density of $\sim10^{6}$ cm$^{-3}$ and temperature of 70 mK. Collisions between the trapped OH sample and supersonic beams of atomic He and molecular D$_{2}$ are observed and absolute collision cross sections measured. The He--OH and D$_{2}$--OH center-of-mass collision energies are tuned from 60 cm$^{-1}$ to 230 cm$^{-1}$ and 145 cm$^{-1}$ to 510 cm$^{-1}$, respectively, yielding evidence of redu…