Intercalated graphite dispenser for ultracold-atomic experiments produces pure rubidium vapors
Intercalated graphite dispenser for ultracold-atomic experiments produces pure rubidium vapors lead image
Chromate salt dispensers, used to control the release of evaporated alkali metals such as rubidium, are ubiquitous tools in modern ultracold atomic experiments. Especially relevant in the growing field of compact atomic sensors, they are compact and easy to handle. But they have relatively low capacity and can emit unwanted gas under certain conditions.
Researchers developed a dispenser that is based on highly oriented pyrolytic graphite (HOPG) intercalated with metallic rubidium. The dispenser holds significantly more rubidium—up to about 100 milligrams—than commercially available chromate salt dispensers of similar volume.
HOPG, a highly pure and ordered form of synthetic graphite with well-aligned crystallites, can absorb large amounts of chemicals between its graphene-like layers, a phenomenon known as intercalation. Using intercalated HOPG (IHOPG) as the dispenser material has been investigated in vapor deposition studies, but no studies of its compatibility with ultrahigh vacuum or modern ultracold-atomic experiments have previously been conducted.
“This dispenser produces extremely pure rubidium vapors using intercalated graphite,” author Rudolph Kohn Jr. said. “Intercalation of cesium, potassium and lithium into HOPG have also been demonstrated in the literature, which suggests that IHOPG dispensers could be made for those alkali metals as well.”
The researchers experimented with IHOPG samples with different levels of order and found the samples with higher crystallographic order loaded and dispensed more reliably. The dispenser prototypes were produced from HOPG samples with mosaic angles of about 0.8 degrees with average grain sizes between 0.5 and 1.0 millimeters.
Source: “Clean, robust alkali sources by intercalation within highly-oriented pyrolytic graphite,” by Rudolph N. Kohn, Matthew S. Bigelow, Mary Spanjers, Benjamin K. Stuhl, Brian Kasch, Spencer E. Olson, Eric A. Imhof, David A. Hostutler, and Matthew B. Squires, Review of Scientific Instruments (2020), The article can be accessed at https://doi.org/10.1063/1.5128120 .
