Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
Science. 2018 May 25;360(6391):900-903. doi: 10.1126/science.aar7797. Epub 2018 Apr 12.
Chemical reactions typically proceed via stochastic encounters between reactants. Going beyond this paradigm, we combined exactly two atoms in a single, controlled reaction. The experimental apparatus traps two individual laser-cooled atoms [one sodium (Na) and one cesium (Cs)] in separate optical tweezers and then merges them into one optical dipole trap. Subsequently, photoassociation forms an excited-state NaCs molecule. The discovery of previously unseen resonances near the molecular dissociation threshold and measurement of collision rates are enabled by the tightly trapped ultracold sample of atoms. As laser-cooling and trapping capabilities are extended to more elements, the technique will enable the study of more diverse, and eventually more complex, molecules in an isolated environment, as well as synthesis of designer molecules for qubits.
化学反应通常通过反应物之间的随机接触进行。超越这一范式，我们在单个、受控的反应中精确地组合了两个原子。实验设备将两个单独的激光冷却原子（一个钠 (Na) 和一个铯 (Cs)）捕获在单独的光镊中，然后将它们合并到一个光偶极阱中。随后，光缔合形成一个激发态的 NaCs 分子。由于原子的超冷样品被紧密捕获，因此能够发现分子离解阈值附近以前未见过的共振，并测量碰撞速率。随着激光冷却和捕获能力扩展到更多元素，该技术将能够在隔离环境中研究更多不同、最终更复杂的分子，以及合成用于量子位的设计分子。
