Measurement of the ozone absorption cross‐section at the 253.7 nm mercury line

The absorption cross‐section of ozone at 253.7 nm is frequently used as a standard for the entire UV wavelength range. The presently accepted value is 1.147 × 10−17 cm², known with an uncertainty of about 2%. The cross‐section has been recently measured by simultaneously monitoring the ozone pressure, the impurities in the ozone gas, the gas temperature and the UV beam intensity. The cross‐section at room temperature was found to be 1.137 × 10−17 cm², having an uncertainty of ±.7%. The improved accuracy will aid a number of ozone experiments including the in situ photometers and Solar Backscatter Ultraviolet instruments.