R2PI detection of the quantum yields of I(2P1/2) and I(2P3/2) in the photodissociation of C2F5I, n-C3F7I, i-C3F7I and CH3I

Resonant two-photon ionization R2PI has been applied to the measurements of the quantum yields ϕ of iodine atoms in the fine structure states 2P1/2 and 2P3/2 arising in the UV-photodissociation process (λ=266 and 355 nm) of the perfluoroalkyliodides C2F5I, n-C3F7I and i-C3F7I as well as of methyl iodide CH3I (λ=266 nm). The measured values of the quantum yields of the excited state (2P1/2) of the I atoms are found to be ϕ266∗=0.921±0.010 and ϕ355∗=0.178±0.025 for C2F5I, ϕ266∗=0.919±0.011 and ϕ355∗=0.296±0.029 for n-C3F7I, ϕ266∗=0.900±0.015 and ϕ355∗=0.396±0.034 for i-C3F7I, and ϕ266∗=0.71±0.03 for CH3I. The results obtained show that the quantum yield ϕ266∗ of the excited state atoms I(2P1/2) in the photodissociation process of the perfluoroalkyliodides differs noticeably from unity which has previously been assumed or measured for these molecules.