| Summary: | 碩士 === 中原大學 === 化學研究所 === 90 ===
A low cost but highly effective experiment has been performed to simulate those photodesorptive reactions of the water ice on the comet. The rate of the total mass loss of water ice is measured and the results can be compared with the data collected from the satellite to investigate the formation of the atmosphere of comet, as well as to explain the real chemical and physical circumstances of the interstellar space. The light source used in this experiment comes from the synchrotron radiation of electron that has an intensity of 1.887 x 1012 photon / (s‧cm2). The facilities are located at the Synchrotron Radiation Research Center (SRRC) of the Excutive yuan.
Experimental results show that the photodesorption has no direct relationship with the sublimation of the water ice resulted from the thermal effect of light. The products from the photodesorption depend on the composition of the water ice. For the pure water ice, the particles’ mass sputtering from the ice surface includes 2（H2）、16（O）、17（OH，NH3）、18（H2O）and 32（O2）. For the ice by mixing CO2 and H2O , the particles’ mass sputtering from the surface includes 2（H2）、12（C）、14（N, CH2）、15（CH3）、16（O, CH4）、17（OH, CH5+, NH3）、18（H2O）、28（N2, CO）、32（O2, CH3OH）、40（Cyclo C3H4）and 44（CO2, C3H8）. The particles with mass of 68, 69, 70 have been measured as well, while their chemical composi- tions are still needed to be determined.
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