Photoionization of hot radicals:: C2H5,n-C3H7, and i-C3H7 -: art. no. 204301

The combination of ion-imaging and vacuum-ultraviolet (vuv) single-photon ionization is used to study the internal energy dependence of the relative photoionization yields of the C2H5,n-C3H7, and i-C3H7 radicals following the 266 nm photodissociation of the corresponding alkyl iodides. The comparison of the ion images obtained by vuv photoionization of the radical with those obtained by two-photon-resonant, three-photon ionization of the complementary I P-2(3/2) and I-* P-2(1/2) atoms allows the extraction of the internal energy dependence of the cross sections. Factors influencing the appearance of the ion images in the different detection channels are discussed, including the secondary fragmentation of the neutral radicals, Franck-Condon factors for the photoionization process, and the unimolecular fragmentation of the parent photoions. (c) 2005 American Institute of Physics.