Decay dynamics of the CN*(B²Σ⁺) and XeF*(B²Σ⁺ and C²Π_3/2) states

The fluorescence decay of CN*(B ²Σ⁺) and XeF*(B ²Σ⁺ and C²Π _3/2) radicals has been investigated following photodissociation of ICN and XeF₂, respectively. Pulsed synchrotron radiation from the Stanford Synchrotron Radiation Laboratory was used as an excitation source so that the fluorescence decay could be monitored directly. Pressure-dependent studies were carried out to separate the effects of collisional quenching from those of radiative decay. The radiative lifetimes derived for the CN*(B ²Σ⁺), XeF*(C ²Σ⁺), and XeF*(C ²Π_3/2) radicals are 70.5±1.6, 14.20.2, and 98±10 nsec, respectively. The collisional fluorescence quenching rate for the CN*(B ²Σ⁺) state by ICN was determined to be (1.15±0.04)×10^-9 cm³ sec^-1(294 K). In addition to the CN*(B ²Σ ⁺) fluorescence observed from ICN excitation, a very fast fluorescence component was observed which is attributed to radiative decay of valence (and/or Rydberg) excitations in ICN.