Laser spectroscopy of the 109.1 nm transition in neutral Cs

The absorption of tunable coherent VUV radiation is used to measure fine-structure splitting and oscillator strength and to estimate the hyperfine splitting of the Cs 109.1 nm transition which originates on a quasi-metastable level. It is noted that this transition in Cs is an example of a transition which originates from slowly autoionzing quasi-metastable levels of alkali-like atoms and ions.