EXPERIMENTAL-DETERMINATION AND CALCULATION OF THE COLLISION RELAXATION RATES IN THE 5 (2)P(1/2) AND 5 (2)P(3/2) LEVELS OF ATOMIC IODINE

Pressure broadening of the hyperfine lines of the P-2(1/2)-P-2(3/2) atomic iodine transition is analyzed from the emission line shapes. Collisions with Ar and O2 in the 0-100 Torr range were examined as well as pressure broadening due to I2 in the 0-15 Torr range. Pressure broadening coefficients alpha were determined: alpha (O2) = 4.8 (3) MHz/Torr and alpha (Ar) = 3.6 (3) MHz/Torr. In the case of I2, alpha (I2) is estimated to be (35 +/- 10) MHz/Torr in the 0-5 Torr range. In addition, pressure broadening coefficients were calculated using the impact approximation. In this approximation relaxation cross sections are calculated between hyperfine levels of the I atom. Estimates of the relaxation rates between the hyperfine levels of I(P-2(3/2)) and I(P-2(1/2)) are deduced from these results, for both elastic and inelastic processes. Experimental and theoretical results are in reasonable agreement.