Searching for the 671nm transition of Lithium - 7

This project aims to measure the ionization threshold by determining the energy of np states from n=10 up to ionization using a single photon and resolve a discrepancy between previous experimental measurements and the current theoretical calculations. As a first step, we observed the spectrum of the 2s →2p transitions with a 671 nm laser.

An oven was used to heat the lithium to about 700 K and create an atomic beam. The laser was directed through the vacuum chamber to overlap perpendicularly with the lithium beam. We monitored the transmitted laser light while scanning the laser frequency up and down.

We observed clear absorption features of the 2s→ 2p transition in lithium using the 671 nm laser. These results confirm the setup is ready for future measurements with the 235 nm laser to probe higher energy states.