Enhancement of the sensitivity of recording the fluorescence of the iodine-129 isotope excited by 633 nm He–Ne laser radiation

An investigation was made of the influence of temperature and of the frequency of the exciting radiation on the fluorescence of molecular ¹²⁹I vapour excited by 633 nm He–Ne laser radiation. Heating of the iodine vapour and a shift of the exciting radiation frequency by 2 GHz toward shorter wavelengths, relative to the centre of the ²⁰Ne gain profile, enhanced by almost an order of magnitude the sensitivity of detection of ¹²⁹I by the laserinduced fluorescence method. The main contribution to the fluorescence signal came from the 6–3 P(33) absorption line.