Researchers at the Van Swinderen Institute in Groningen have discovered a new method for immobilizing individual molecules for precision studies. Their article has just been published in Physical Review A.
The research is being conducted within the eEDM program of Nikhef and the University of Groningen. PhD student Bart Schellenberg from Steven Hoekstra’s eEDM group is the first author of the PRA article.
In precision research, it is common practice to slow down beams of molecules electromagnetically and cool them further with lasers. For the most precise measurements, it is then best to trap the molecules in an optical trap for laser studies.
The laser cooling step currently requires a dozen precisely tuned lasers. With the newly proposed technique, the absorption of a single photon is sufficient to lure a molecule into the trap, making the experiment much simpler. Moreover, this approach allows measurements to be made on molecules for which laser cooling is not possible due to their quantum structure.
The eEDM program focuses on precision measurements of the fundamental properties of the electron. It makes use of the extremely high electric fields inside some polar molecules. To study the behavior of electrons there, such molecules must be slowed down and stopped in a so-called optical trap.
The new method uses an electric field to reflect beams of incoming molecules such as barium fluoride (BaF) like a mirror. At the turning point, the molecules remain stationary for a moment, and a single photon is sufficient to knock the molecule to a higher energy level.
In the work that has now been published, the researchers have found a method to capture the molecules immediately after they bounce back in the optical trap for further study.
The group in Groningen will first test the new procedure and eventually apply it in the institute’s molecular setup. The goal of the eEDM research is to measure the electrical symmetry of the electron with record precision.
According to the Standard Model of particle physics, electrons are perfectly symmetrical point particles. Even small deviations from this can be an indication of new physics that may not be accessible to large particle accelerators such as those at CERN.
