Knowledge Bank

Using an F-center laser and the technique of optogalvanic detection we have observed transitions among low-lying Rydberg states of lithium, neon and argon in hollow cathode discharges in the region from $2600-4000cm-1$. Most of the fifty-one observed lines in neon, the single lithium transition and the fifty-two observed lines in argon have been assigned. The transitions in neon occur among the $4s\to 4p,4p\to 4d,4d\to 4f$ and $5s\to 6p$ arrays and those of argon between the $3d\to 5p,5s\to 5p$ and $5p\to 5d$ arrays while that in lithium is the $3s\to 3p$ transition. The high signal to noise ratios we have observed indicate the potential of this technique for studying excited species in discharges and point to the possibility of employing it for the study of highly excited molecules.