The Production of IF(B3Π) in the
248 nm Laser Photolysis of
Fluorine/Alkyl Iodide Mixtures
D. Raybone,1,2 T. M. Watkinson,1J. C. Whitehead,1and F. Winterbottom1
Received20 May 1988
Abstract
Sustained visible emission in the region 440–850 nm from the B → X system of IF is
observed when a gas phase mixture (~0.5 mbar) of an alkyl iodide with F2 in He is
photolysed at 248 nm by a KrF laser. The total intensity and decay rate of the IF(B)
emission is a strong function of the identity of the alkyl iodide and can be correlated with
the 248 nm photon yields for the production of I*(2p1/2). The half-lives for the IF(B)
decays range from 5 μs for t-C4H9I to 770 μs for n-C3F7I. Decay curves for the I*(2p1/2)
concentrations are also measured by atomic fluorescence. The mechanism for IF(B)
formation in these systems is discussed and it is suggested that IF(B) is produced either
by a recombination process involving I* and F atoms or by multistep collisional
excitation of ground state IF(X) by I*. The F atoms can be produced following the
photolysis pulse by the reaction of the alkyl radical with molecular fluorine and IF(X)
can result either from the reaction of F atoms with the alkyl iodide or from a dark
reaction between molecular fluorine and the alkyl iodide.