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[B-4.3 Studies on Photodissociation Rates of Atmospheric Compounds]

[Contact Person]

Isao H. Suzuki
Section Chief, Quantum Radiation Division,
Electrotechnical Laboratory,
Ministry of International Trade & Industry
Umezono 1-1-4, Tsukuba, Ibaraki 305 Japan
Phone +81-298-58-5663, Fax +81-298-58-5673

[Total Budget for FY1990-1992]

21,815,000 Yen

[Abstract]

　In order to estimate photodissociation rates of greenhouse gases at several altitudes, photoabsorption cross sections of these compounds have been measured in the ultraviolet region. Day-averaged intensities of solar ultraviolet radiation at several altitudes were calculated using the literature data for equinox in a latitude of 0゜. Photodissociation rates were estimated using the observed cross section data and the calculated radiation intensities. Quantitative studies on the quantum yields of the photodissociation process have been performed using the two-color laser induced fluorescence method, the electron-impact ionization mass spectrometer and the excimer laser photolysis of shock heated samples. The quantum yields for the photolysis (193nm) of C₂H₂, H₂S, N₂O, CCl₄ and so forth were decided.

[Key Words]

Greenhouse radiation, Photoabsorption cross-section, Solar ultraviolet radiation, Quantum yield, Laser-induced-fluorescence