Typically, if you want to understand the foundation of something, building from the ground up sounds like a sensible approach. However, researchers in Dr. Ni’s group at Harvard have taken this idea a step further by building molecules one atom at a time. The group’s goal is to better understand the minimal requirements and exact properties of chemical reactions. For comparison, while every chemistry class in high school is taught using nearly a trillion trillion atoms (~one mole), the Ni group is using the very minimum number — precisely two.
Chemistry has traditionally been studied in a controlled, but ensemble averaged fashion. That means that there are a variety of local differences between each given individual molecular reaction that are ignored or simply not even observable. In Liu et. al., the researchers begin the experiment by picking out a single sodium atom and a single cesium atom from a hot atomic vapor with tweezers made from lasers — a technique known as optical tweezers — and bring them together to form an optical “beaker”, in which the two atoms can now react.
Lee Liu, the senior graduate student on the project, describes this as “stripping a chemical reaction down to the bare essentials: two atoms, and something to add or remove energy — in this case a laser photon.” He also points out that this work isn’t only for the microscopic insight of chemical reactions, but also “it is an important first step to making ‘custom’ molecules that could serve as qubits (building blocks of a quantum computer).”
Thank you to Lee Liu, the senior graduate student in the Ni group from Harvard University, for his explanation of his research and its impact on future studies.