RESONANT 2-PHOTON IONIZATION DETECTION OF ATOMIC IODINE RESULTING FROM PHOTODISSOCIATION OF ALLYL IODIDE UNDER VIBRATIONAL (C-H OVERTONE) EXCITATION

The resonant two-photon ionization (R2PI or (1 + 1) REMPI) method was used to achieve highly sensitive detection of atomic iodine. The atoms were excited and ionized by tuned VUV and visible radiation, subsequently. The formation of iodine atoms in the fine structure states 2P3/2 and 2P1/2 was observed after the photolysis of allyl iodide (C3H5I) by UV radiation (355 nm). The atomic iodine absorption at 151.469 and 159.358 nm corresponding to the transitions 2P3/2-(3P2) 5d[3]5/2 and 2P1/2-(3P2)5d[2]3/2, respectively, were obtained under both collisional and collisionless conditions. It was shown, that the distribution of I atoms on hyperfine structure levels, produced from the photodissociation Of C3H5I did not differ from the equilibrium one. The time-profile of atomic iodine appearance was measured when C3H5I was excited at the C-H vibrational overtone frequency (nu = 5, lambda = 703.5 nm).