Chemical evolution of CO:H2S ice mixture under 1 keV electron irradiation

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/92550

Title:	Chemical evolution of CO:H2S ice mixture under 1 keV electron irradiation
Authors:	李智曜;Li, Jr-Yau
Contributors:	物理學系
Keywords:	星際冰晶;硫化氫;一氧化碳;電子作用;紅外光譜;質譜儀;含硫分子;interstellar ice;hydrogen sulfide;carbon monoxide;electrons;infrared spectroscopy;mass spectroscopy;S-bearing molecules
Date:	2023-07-25
Issue Date:	2024-09-19 15:55:38 (UTC+8)
Publisher:	國立中央大學
Abstract:	硫是宇宙中第十豐富的元素，其中H2S是第三豐富的硫物種，僅次於S和HS。此外，H2S被認為是眾多硫分子的重要前導物質，如OCS、CS2、以及SO2分子。在這項研究中，我們通過在CO:H2S混合冰晶照射1 keV的電子，模擬宇宙射線產生的次級電子，研究不同環境對含硫分子的化學衍化影響。我們的結果發現：（一）在較高的CO:H2S比例中，CO和H2S分子具有較低的消耗截面。（二）在實驗中觀察到的主要生成物為CO2、OCS、SO2和CS2分子。其中CO2、OCS和SO2分子的生成速率隨著CO:H2S混合冰晶的比例上升而增加。（三）在所有比例CO:H2S混合冰晶的情況下，消失的硫原子都來自於Sx物種的生成。此外，我們發現CO2和CS2分子的吸收帶對周圍環境（冰晶混合物的組成和其中各分子的相對比例）非常敏感，特別是CO2分子的柱密度，會被紅外吸收特徵的形變及電子激發脫附兩者嚴重影響。;Sulfide is the tenth most abundant element in the universe. The hydrogen sulfide (H2S) is the third most abundant sulfur species, following sulfur atoms and sulfanyl radicals, and serves as an important precursor for S-bearing molecules such as OCS, CS2, and SO2. In this study, we investigated the effect of environmental conditions on the chemical evolution of S-bearing molecules by irradiating CO:H2S ice mixtures with 1 keV electrons, simulating secondary electrons generated from cosmic rays. Our results revealed the following findings: (I) Higher CO:H2S ice mixture ratios lead to lower depletion cross section of parent molecules (CO and H2S). (II) The major products observed were CO2, OCS, SO2 and CS2. The formation rates of CO2, OCS, and SO2 increased with higher CO:H2S ice mixture ratios. (III) In all cases of CO:H2S ice mixtures, the missing sulfur is attributed to the presence of Sx species. Furthermore, the bands of CO2 and CS2 molecules were found to be sensitive to the surrounding environment (the composition of ice mixtures and the relative proportions of each molecule within them), and the CO2 column density was significantly affected by the interaction between infrared feature distortion and electron stimulated desorption (ESD).
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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