Measurements of pressure-broadening coefficients for the F' = 3 ← F = 4 hyperfine line of the 2P1/2 ← 2P3/2 transition in atomic iodine

We describe a series of measurements of pressure-broadening coefficients for the F' = 3 ← F" = 4 line of the 2 P 1 / 2 ← 2 P 3 / 2 transition in atomic iodine. This is the optical transition of the chemically pumped atomic iodine laser (COIL), and our results are relevant to a more complete understanding of this important class of high-power lasers. The measurements were made in sealed cells using an argon ion laser to photodissociate molecular iodine and a tunable diode laser to probe directly the atomic transition. We measured broadening coefficients for three bath gases: He, N 2 , and O 2 . Full absorption line shapes were recorded as a function of the added bath gas pressure and the following values were obtained at room temperature: (Δv/ΔP H e ) T = 2 9 6 K = 3.2 ′ 0.3 MHz/Torr, (Δv/ΔP N 2 ) T = 2 9 6 K = 5.5 ′ 0.6 MHz/Torr, and (Δv/ΔP O 2 ) T = 2 9 6 K = 5.0 ′ 0.5 MHz/ Torr; where Δv is the full width at half-maximum. We also measured the temperature dependencies of the He and O 2 broadening coefficients over the range 296 K < T < 775 K. We quote the temperature-dependent values as (Δv/ΔP H e ) T = (3.2 ′ 0.3) x (296/T) 0 . 3 6 and (Δv/ΔP O 2 ) T = (5.5 ′ 0.6) x (296/T) 0 . 7 0 . Comparisons to previous measurements are also discussed.