Optogalvanic spectroscopy of the Zeeman structure of argon energy levels close to the ionization limit

Highlights: • Optogalvanic spectroscopy (OG) was used in measurements of the Zeeman structure of atomic argon. • Experimental gJ factors have been determined for 9 energy levels of Ar I. • The gJ data for many other levels of Ar I have been tested and verified. The Lande $g_J$ factors for high lying states of the argon atom by laser optogalvanic spectroscopy were measured, in most cases with an uncertainty of less than 0.005. The Zeeman structure of 12 argon lines with wavelengths in the range 598.7-612.8 nm was investigated. We determined Lande $g_J$ factors for 9 odd parity levels and verified the data for several other levels.