Isogenous series

Isogenous is a term occasionally used in spectroscopy that denotes when two or more spectroscopic series of transition from a common state. The word was first used in this context by Stone and Barrow in 1975.[1] In this case, an excited state of gaseous ${\displaystyle Te_{2}}$ was pumped by an Argon ion laser; the excited state then relaxed to two closely separated low lying states giving two series of emission lines with a common origin.