Highlighting the fine level of control modern chemists possess, researchers have trapped two single atoms - sodium and cesium - in separate "optical tweezers" and then maneuvered them together, resulting in a single molecule of sodium cesium (NaCs) with unique properties. The techniques involved in isolating exactly two atoms in this way, to prepare a single molecule, could enable the study of more diverse and more complex molecules, in isolation, as well as allow the synthesis of designer molecules for use in quantum information applications. Typically, when chemists run reactions, they mix up many reacting partners in hopes that those partners will productively collide. It's possible to manipulate atoms more deliberately than this with a scanning tunneling microscope tip, but even this process has limitations. Prior work seeking to more finely manipulate atoms towards more specific chemical reactions has achieved a chemical reaction using a single atomic ion immersed in a gas of many atoms. Here, however, Lee Liu and colleagues sought to achieve a reaction starting from just two atoms. To do so, they held a laser-cooled atom of sodium in an optical tweezer of one wavelength and a laser-cooled atom of cesium in an optical tweezer of another wavelength. Then, using a pulse of light, they maneuvered the individual laser-cooled atoms (with laser cooling being important for quantum applications) into a single NaCs molecule, which exhibited an excited state. Studying this molecule with spectroscopy revealed properties previously unobserved in NaCs, the authors say. Their approach paves the way to studying collisions between atoms and molecules in the "cleanest" environment possible.
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Journal
Science