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: (Δν/Δ P He ) T =296K = 3.2 ± 0.3 MHz/Torr, (Δν/Δ P N 2 ) T =296 K = 5.5 ± 0.6 MHz/Torr, and (Δν/Δ P O 2 ) T =296 K = 5.0 ± 0.5 MHz/Torr; where Δν 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 (Δν/Δ P He ) T = (3.2 ± 0.3) × (296/ T ) 0.36 and (Δν/Δ P O 2 ) T = (5.5 ± 0.6) × (296/ T ) 0.70 . Comparisons to previous measurements are also discussed.