冰晶中光脫附總質量損失之研究

Photodesorbed Total Mass Loss of Water Ice

周娜(Nina Chow)

指導教授 ： 鄭建業

中原大學/理學院/化學研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200198

摘要

我們研究室以所設計的低成本但高效能的實驗，進行模擬彗星冰晶照光所生反應，並觀察冰晶總質量損失的變化率。實驗結果將用來和人造衛星上所收集到的數據比對，以研究彗星大氣的成因並嘗試解釋真實星際太空的物理與化學情境。藉由行政院國科會同步輻射中心的同步輻射光源，於低溫下照射冰晶的光強度可達1.887 x 1012 photon/(s‧cm2)。
實驗的結果發現純水的冰晶，其光的脫附作用與冰在光照時受熱所造成的昇華沒有直接的關係。光脫附的產物依冰晶組成成份而有不同，在純冰晶中，實驗觀測到的脫附粒子有質量為2（H2）、16（O）、17（OH，NH3）、18（H2O）和32（O2）等氣體逸出冰晶表面。 在CO2混合純水的冰晶光脫附實驗中，則觀測到脫附粒子的質量計有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）及44（CO2, C3H8）等，同時觀測到質量為68, 69, 70 的粒子，其物種為何尚未能確定。

關鍵字

光脫附 ； 冰晶

並列摘要

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.

並列關鍵字

photodesorption ； water ice

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