冰晶光脫附總質量損失與其化學產物之研究

Photodesorbed Total mass Loss and Its Chemical Products of Water Ice

周娜(Nina Chow) ； 鄭建業(Cheanyeh Cheng) ； 易台生(Tai-Sone Yih)

《化學》 61卷1期 (2003/03) Pp. 21-29

https://doi.org/10.6623/chem.2003003

摘要

我們設計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。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1.9×10^(12) photon/(s-cm^2)。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。光脫附的化學產物依冰晶組成成份而有不同，在純冰晶中經殘餘氣体分析儀觀測到的脫附粒子有質量為2(H_2)、16(O)、17(OH，NH_3)、18(H_2O)和32(O_2)等氣體逸出冰晶表面。在CO_2混合純水的冰晶光脫附實驗中，觀測到脫附粒子的質量有2(H_2)、12(C)、14(N, CH_2)、15(CH_3)、16(O, CH_4)、17(OH, CH_5^+, NH_3)、18(H_2O)、28(N_2, CO)、32(O_2, CH_3OH)、40(cyclic C_3H4)及44(CO_2C_3H_8)等，另有質量為68, 69, 70的粒子，但其為何物種尚未能確定。

關鍵字

冰晶光脫附 ； 冰晶總質量損失 ； 光脫附化學產物

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 used 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 1.9x10^(12) photon (s．cm^2). The facilities are located at the Synchrotron Radiation Research Center (SRRC) of the Executive 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 chemical products from the photo desorption depend on the composition of the water ice. For pure ice, the particle's mass sputtering from the ice surface detected by the residual gas analyzer includes 2(H_2)、16(O)、17(OH，NH_3)、18(H_2O) and 32(O_2). For ice of mixing CO_2 and H_2O, the particles' mass sputtering from the surface includes 2(H_2)、12(C)、14(N, CH_2)、15(CH_3)、16(O, CH_4)、17(OH, CH_5^+, NH_3)、18(H_2O)、28(N_2, CO)、32(O_2, CH_3OH)、40(cyclic C_3H_4) and 44(CO_2, C_3H_8). The particles with mass of 68, 69, and 70 have been measured as well while their chemical compositions are still needed to be determined.

並列關鍵字

Photodesorption of water ice ； Total mass loss of water ice ； Chemical products of photodesorption