UV-photolysis of HI center dot center dot center dot CO2 complexes in solid parahydrogen: Formation of CO and H2O

The photochemistry of (HI)(m)...(CO2)(n) (m, n = 1, 2,...) complexes trappe d in solid parahydrogen was studied by Fourier transform infrared absorptio n spectroscopy. Photolysis of the HI in the HI ...(CO2)(n) complexes result s in the generation of carbon monoxide and water molecules along with iodin e atoms. Analysis of the observed spectra leads to the conclusion that the energetic hydrogen atom produced by the photolysis of HI initiates the reac tion with one of the CO2 molecules in the complexes as H + CO2 --> OH + CO, which is followed by the secondary reaction of OH radicals with the matrix hydrogen as OH + H-2 --> H2O + H. These four-atom reactions are of practic al importance in combustion processes as well as of theoretical importance in fundamental chemical dynamics. The result of the present study shows the usefulness of the parahydrogen matrix for fundamental study of photochemis try with the use of weakly bound complexes.