Photochemistry of Iodobenzene Adsorbed on Sapphire(0001)

Iodobenzene (C 6 H 5 I) dosed on sapphire(0001) at 110 K adsorbs molecularly and desorbs with a peak near 187 K, depending slightly on coverage. Irradiation with 193 nm photons induces dissociation attributable to photon absorption by C 6 H 5 I and C−I bond cleavage. A measurable fraction of the products are ejected during irradiation. Normalized to the initial intensities, the I XPS signal decays 2.5 times faster than the C signal. The cross sections for the loss of C 6 H 5 I, I, and C are (2.8 ± 0.3) × 10 -18, (6.6 ± 0.7) × 10 -19, and (2.7 ± 0.3) × 10 -19 cm 2, respectively. Benzene (C 6 H 6 ) and biphenyl (C 12 H 10 ) appear in TPD at temperatures consistent with desorption-limited processes.