Mark N. Spencer

Measurement of self-broadening of the ozone v3 transitions

Abstract Self-broadening coefficients have been measured for a number of rovibrational lines in the v 3 band of ozone, in the frequency range 1015–1058 cm -1 , with J values between 0 and 27, and over a range of K a values. A multiparameter non-linear least-squares fitting procedure is used to reduce the data, and the sensitivity of the procedure to instrument line width, weak satellite features, and absolute intensity has been examined. The retrieved coefficients are compared with millimeter-wave broadening coefficients, directly measured rotational relaxation times, and recently suggested empirical representations.

Nitrogen broadening of ozone ν3 rovibrational transitions at 220 K

Abstract Nitrogen broadening coefficients of 33 rovibrational transitions in the ν3 band of ozone were measured at 220 K to an accuracy of approximately 5%. These values represent the first broadening determinations below room temperature for the 9.6 μm spectral region and are useful for calibration of theoretical calculations of the broadening and its temperature dependence.

Rotational relaxation contributions to infrared pressure broadening in ozone

Rotational relaxation times in ozone–ozone collisions have been measured for selected rovibrational levels using the time‐resolved infrared double‐resonance technique. Rotationally inelastic processes account for at least 90% of the measured pressure‐broadening rate. The rotational‐state dependence of the relaxation cross sections is in good accord with the collision models used in current theories of pressure broadening. The V–V energy transfer rate between symmetric and asymmetric stretching modes of ozone has also been measured; the V–V cross section is approximately 15 A2, about an order of magnitude smaller than that for rotational energy transfer.

Temperature dependence of nitrogen broadening of ozone ν3 rovibrational transitions

Abstract We report N 2 -broadening coefficients for rovibrational transitions of the ν 3 band of ozone in the temperature range 180–296 K. We assume a power law dependence of the temperature for these coefficients, with a temperature exponent n . For the 21 transitions we measured, the average value of n is 0.74 and is well within experimental error of the theoretically predicted value of 0.77. The significance of this parameter in modeling atmospheric IR absorbance due to ozone is discussed.

Temperature dependence of oxygen-broadening of ozone ν3 rovibrational transitions

Abstract We report O2 broadening coefficients for rovibrational transitions in the v3 band of ozone for temperatures between 165 and 280 K. We assumed a power-law dependence of the temperature for these coefficients, with a temperature exponent n. For the 25 transitions we measured, the average value of γ0 is 0.071 cm-1 atm-1 and the average for n is 0.67.