One out of Two...

Collision course: two atoms held in optical tweezers before forming a molecule
(Courtesy: Lee Liu and Yu Liu)

Topics: Chemistry, Laser, Optical Physics, Optical Tweezers, Particle Physics

A single molecule has been created by combining individual atoms of sodium and caesium, using optical tweezers to guide them into place. The technique, devised by Lee Liu and colleagues at Harvard University and Harvard-MIT Health Sciences and Technology, could help chemists to study chemical reactions far more precisely by giving them control over the individual atomic and molecular collisions. The team hopes that their method will be used in a variety of fields to create diverse, complex molecules, allowing for discoveries of previously unforeseen molecular properties.

Conventional studies of chemical reactions involve observing the macroscopic results of large numbers of collisions of atoms and molecules – rather than studying individual collisions. Currently, chemists need to compare experimental reaction rates with theoretical models to calculate the probabilities of individual collisions taking place – a process that is fundamental to the understanding of chemistry. An alternative, and more precise, technique is to study interactions between individual atoms and molecules – something that requires great experimental dexterity.

To begin their interaction process, Liu and colleagues use magneto-optical traps to prepare reservoirs of stationary atoms of sodium and caesium at just a few hundred microkelvin. “Cooling and controlling atoms and molecules to temperatures where they are standing still allows for easier manipulations of their properties, interactions and reactions,” explains team leader Kang-Kuen Ni.

Optical tweezers create a single molecule from two atoms, Sam Jarman, Physics World