Third harmonic generation by iodine atoms and methyl iodide molecules

Abstract

A dilute gas of I( 2P o 1 2 ) atoms serves as a medium for optical third harmonic generation (THG) of wavelengths a little shorter than 206.2 nm, the wavelength of an atomic transition. It is also shown that a gas of the polyatomic molecule CH 3I exhibits THG at wavelengths slightly longer than the first Rydberg transition at 201.2 nm. It is believed that this is a general phenomenon for molecules with sharp Rydberg transitions.