不同電子能量作用下對N2O冰晶的衍化影響

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/92067

Title:	不同電子能量作用下對N2O冰晶的衍化影響
Authors:	姜瑋琪;Jiang, Wei-Chi
Contributors:	物理學系
Keywords:	一氧化二氮;星際冰晶;電子激發脫附;電子穿透深度;N2O;interstellar matter;E-gun irradiation;electron penetration depth;desorption
Date:	2023-07-27
Issue Date:	2023-10-04 14:54:37 (UTC+8)
Publisher:	國立中央大學
Abstract:	天文觀測顯示在人馬座恆星形成區域有氣態N2O分子的存在，並且具有N-O鍵的分子可能是前生物分子(prebiotic molecules)的潛在前體(precursor)。星際冰晶在冷星雲環境中會因為遭受宇宙射線的照射而產生化學衍化，宇宙射線在冷星雲環境中會因為與氫分子、氫原子的交互作用而產生許多二次電子。過往的研究對於冷星雲環境中的二次低能量電子(≤ 1000 eV)照射冰晶分子所引發的衍化研究並不多，因此本論文將探討在不同低能量電子(600–1000 eV)照射下對N2O冰晶的衍化影響。研究結果顯示當入射電子能量越高時，電子的穿透深度也越深，導致有更多的N2O分子被消耗形成產物(如：NO, O3, NO2, N2O4, N2O5…)。N2O冰晶在低能量電子的作用下，其消耗行為可以分為前期由化學衍化主導與後期由電子激發脫附(electron stimulated desorption)主導。當N2O冰晶的消耗由電子激發脫附機制主導後，產物產量與脫附速率皆達相對穩定的狀態。 ;Previous studies indicate that gaseous N2O molecules have been observed in star-forming regions(Sgr B2(M)) and that molecules with N-O bonds may be the potential precursors for prebiotic molecules. Interstellar ice mantles undergo chemical evolution in cold dense cloud environments due to cosmic ray irradiation. Cosmic rays interact with hydrogen molecules and hydrogen atoms, producing numerous secondary electrons(δe-) in cold molecular cloud environments. Previous studies on the evolution of ice molecules irradiated by low-energy electrons (≤ 1000 eV) in cold dense cloud environments are limited. Therefore, this study investigates the evolutionary effects of N2O(s) under irradiation by different low-energy electrons (600–1000 eV), which is equivalent to the secondary electrons produced by the collision of cosmic ray ions with molecules. In this study, we use different incident electron energies at low temperature of 13 K to influence the chemical evolution. We found that as the energy of incident electrons increases, their penetration depth also increases, leading to the depletion of more N2O molecules and the formation of products such as NO, O3, NO2, N2O4, N2O5. The depletion behavior of N2O(s) under the fluence of low-energy electrons can be divided into an initial stage dominated by chemical evolution and a later stage dominated by electron-stimulated desorption. When the depletion of N2O(s) is dominated by the electron-stimulated desorption mechanism, both the product yield and desorption rate reach a relatively stable phenomenon as a function of fluence.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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