Electron microscopes and other advanced accelerators depend on photocathodes, which produce electron beams that make them work. But in order for such advanced devices to continue functioning, the photocathodes must occasionally be refreshed or rebuilt, which typically requires opening the devices and disturbing the vacuum within.
A new study published in the journal Applied Physics Letters has found that using graphene in place of traditional materials like silicon, which breaks down after prolonged use, can significantly decrease the amount of work needed to replace photocathodes, reducing downtime for the devices.
“The machines that rely on these electron emitters typically operate under high vacuum,” said Los Alamos National Laboratory physicist Hisato Yamaguchi. “By choosing graphene over materials like silicon or molybdenum, which tend to degrade during use, we can clean the substrate and redeposit electron-emitting materials without opening the vacuum. This can dramatically reduce downtime and labor involved in replacing photocathodes.”
The team suggested that photocathodes were more resilient when placed on graphene surfaces because the emitter atoms had a weaker bond with the carbon layer underneath. By using graphene as a substrate, the electron emission rate of the photocathode remained consistent even with multiple uses.