Water vapour concn. measurement in a gas - by irradiating to cause photodissociation and generation of excited hydroxyl radicals

摘要

The water vapour concn. is a gas sample measured by irradiating the gas with radiation of wave length 1350 angstroms which causes partial photodissocation of the water vapour, thus creating excited hydroxyl radicals. The intensity of emission at about 3000 angstroms is measured, this being proportioned to the water vapour concn. in the gas. The radiation may include a wavelength of 1216 angstroms, i.e. the Lyman alpha line of hydrogen. Appts. used includes a radiation source, e.g. hydrogen lamp, and a detector sensitive at around 3000 angstroms.