January 2025
(aka: the trashiest laser spectroscopy ever)
Common and extremely cheap neon indicator lamps can be used instead of hollow cathode lamps in an optogalvanic laser spectroscopy setup. Such lamps are found everywhere in electrical appliances, and it seems they can also be used as laser wavelength references of a remarkable accuracy, especially for something so ridiculously cheap :)
Using the same setup and lasers as in the previous article, in addition to what looks like the Fe I line at 1409.9nm, a much stronger line can be detected near 1391.2nm. If you have any idea where it comes from, please let me know - ASD does not return any obvious candidates. Of course, those lamps may be more useful in the red/yellow/green region where neon has many well-known lines which I expect to be very strong.
Comment from Erik Streed re. 1391.2nm: "Water vapor. [link]
Lots of water sticks to stuff like glass even if the vacuum pressure is initially low."
