화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.103, No.45, 9154-9162, 1999
Photochemistry of HNCO in solid Xe: Channels of UV photolysis and creation of H2NCO radicals
Photolysis of HNCO at wavelengths between 266 and 193 nm is studied in solid Xe with FTIR and laser-induced fluorescence methods. The channels HNCO --> H + NCO (a) and HNCO --> NH + CO (b) are operative in a Xe matrix. Channel b produces bath. isolated fragments and NH CO complexes as characterized by the CO absorption. The MP2/6-311++G(3df,3pd) calculations are presented for the NH-CO complexes and compared with the experimental data. Photolysis of NCO produces mainly NO + C. A part of the carbon atoms form C-2 after which C-2(-) is created in a photoinduced charge transfer reaction. For comparison, in solid Kr, photolysis of HNCO produces additionally HOCN but this channel is absent in a Xe matrix. Upon annealing of the partially photolyzed matrix at 50 K, hydrogen atoms an mobilized and a radical H2NCO is formed by a reaction of a hydrogen atom with a HNCO molecule. Four IR absorptions of H2NCO an observed and they agree well with the MP2/6-311++G(3df,3pd) calculations. The assignment is supported by experiments with DNCO. The threshold for the photodecomposition of H2NCO is between 365 and 405 nm.