Rydberg tagging detection system expands capabilities of studying low-temperature collisions

Characterizing chemical reactions at temperature as low as a few Kelvins is a crucial step in better understanding how they occur in outer space and the upper atmosphere. Rydberg tagging time-of-flight mass spectrometry has garnered interest for detecting such reactions with high translational resolution. One paper looks to push this technique even further.

Li et al. present a new system for Rydberg tagging detection and have demonstrated it with a prototypical atom-diatom reaction at low collision energies. The crossed-molecular-beam apparatus uses a multi-channel detection scheme with 15 microchannel plate detectors that has allowed them to simultaneously accumulate time-of-flight spectra over scattering angles ranging up to 112 degrees.

“Compared with the similar detection scheme in previous works, the major progress of this work is the great enhancement of data accumulation efficiency,” said author Chunlei Xiao. “By using as many as 15 detectors, the data accumulation efficiency has been boosted by an order of magnitude.”

By increasing the number of microchannel plate detectors from the standard one to 15, the group’s technique alleviates many of the potential problems associated with time-dependent drift in other elements of the experiment.

After calibrating the setup with an angular distribution of hydrogen atoms from photodissociation of methane at 121.6 nanometers, the researchers tested a reaction in which fluorine was collided with diatomic hydrogen at 6.9 millielectronvolts. They found excellent agreement between the test reaction and previous work.

Xiao hopes the group’s work will generate further interest in low-temperature reactions and looks to use the new technique’s higher efficiency to explore reactions with low collision energies, including those in which quantum effects play a role.

Source: “A crossed-molecular-beam apparatus with multi-channel Rydberg tagging time-of-flight detection,” by Lulu Li, Heilong Wang, Zhirui Jiao, Yu Li, Tao Wang, Xingan Wang, Xueming Yang, and Chunlei Xiao, Review of Scientific Instruments (2020). The article can be accessed at https://doi.org/10.1063/5.0014046 .