2-PHOTON ABSORPTION SPECTROSCOPY OF IODINE MONOCHLORIDE IN THE 5 EV REGION

Two-photon high resolution sequential spectroscopy has been used to excite iodine monochloride from X1Σ+ ground state to the intermediate A3Π1 state and thence to a final electronic state at 4.82 eV. Vibrational and rotational analyses of this state have been carried out for both isotopic species. For I35Cl, Te = 38916.0 cm-1 ωe = 168.99 cm-1, ωexe = 0.357 cm-1 and Be = 0.05685 cm-1. The state probably has Ω = 1 in case (c) coupling approximation. It is also shown how to two-photon technique enables rotational line structure of the A ← X transition to be selectively excited for either isotopic species at a resolution of 500000, from an absorption mixture containing natural iodine monochloride plus its iodine dissociation product at equilibrium vapour pressure. © 1979.