Photo-desorbed Mass Spectrum Analysis on H2O+ CO2+ NH3 Mixed Ice

• Main Authors: Yu-Gan Fan, 范裕淦
• Other Authors: Tai-Sone Yih
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/57318021849343412445

碩士 === 國立中央大學 === 物理研究所 === 91 === A photodesorption simulation on mixed ices under photon irradiation was presented in our studies for understanding the formation and evolution of the chemical composition in our solar system, such as comets and molecular clouds. The mixed ices with ratio of H2O+ CO2 + NH3 = 1: 1: 1 and 1: 1: 4 at 20 K were selected to for the process of photon irradiation. A quadrupole mass spectrometer was employed to detection of desorbed products and the quartz crystal microbalance for determination of mass loss rate. The necessary intense simulation of solar radiation is provided by the High Flux beamline at Synchrotron Radiation Research Center. An ultra-high vacuum system and a cryogenic cold finger were assembled to simulate the astronomical environments. The experimental results on the photo-desorbed mass spectra reveals that desorbed products include H2, NH2, NH3, CO, O2, and CO2 .The obvious difference between those two mixed ices is the abundance. CO is more abundant in the ice of H2O+ CO2 + NH3 = 1: 1: 1 and H2 in the other ice sample. The behavior is also reflected on the mass desorption rate. In the ice of H2O+ CO2 + NH3 = 1: 1: 1, the mass desorption rate is more than that in H2O+ CO2 + NH3 = 1: 1: 4. An effect dominated by hydrogen atom on desorption abundance and chemical pathway is also observed.