H2O+ CO2+ NH3 混合冰晶的光脫附質譜分析; Photo-desorbed Mass Spectrum Analysis on H2O+ CO2+ NH3 Mixed Ice

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題名:	H2O+ CO2+ NH3 混合冰晶的光脫附質譜分析;Photo-desorbed Mass Spectrum Analysis on H2O+ CO2+ NH3 Mixed Ice
作者:	范裕淦;Yu-Gan Fan
貢獻者:	物理研究所
關鍵詞:	冰晶;光脫附;ice;photodesorption
日期:	2003-07-07
上傳時間:	2009-09-22 10:54:28 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	為了更進一步對星際中各物質組成的演化與行成有所了解，例如：彗星、分子雲等。我們設計了一個有關混合冰晶在光子輻射下的光脫附模擬實驗。實驗中，用以模擬光脫附所使用的冰晶成分組成分別為H2O+ CO2+ NH3 = 1: 1: 1與1: 1: 4的比例。實驗過程，藉由一四極式質譜儀對光脫附物質進行量測，而微量秤則用來量測混合冰晶整體質量上的變化。至於模擬的光源係由國家同步輻射研究中心的High-Flux光束線來提供；整個實驗的環境模擬則是架構於一超高真空腔體內並且藉由冷凍機提供所需的低溫環境。從實驗的結果中，我們發現在光子照射過程下，將導致各種演化分子不斷地由冰晶層上脫附出來。其中包含了H2、NH2、NH3、CO、O2及CO2。而相較於實驗中所使用的兩種冰晶樣品，更發現了CO的脫附產量在H2O+ CO2+ NH3 = 1: 1: 1的混合冰晶中是最大量的脫附物，而H2卻是H2O+ CO2+ NH3 = 1: 1: 4的混合冰晶中脫附產量最大的物質。此行為也同樣於質量脫附率上得到相互的應合，在1: 1: 1樣品中的質量脫附率是大於1: 1: 4樣品的。而整合實驗結果後，我們認為氫原子所佔的數量多寡將決定光脫附過程的化學演變路徑，致使各種脫附產物於脫附量上以及產物行成上的差異。 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.
顯示於類別:	[物理研究所] 博碩士論文

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