Temperature dependent photodesorption of CO ices

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/80712

Title:	Temperature dependent photodesorption of CO ices
Authors:	卓筠庭;Cho, Yun-Ting
Contributors:	物理學系
Keywords:	一氧化碳;星際冰晶;光脫附;真空紫外光照射;能量傳遞;Carbon monoxide;Interstellar ice;Photodesorption;VUV irradiation;Energy transfer
Date:	2019-07-31
Issue Date:	2019-09-03 15:00:55 (UTC+8)
Publisher:	國立中央大學
Abstract:	真空紫外光子引發冰晶分子的非熱脱附效應，可以用來解釋冷星雲與星際間觀測到大量的氣態一氧化碳分子的成因。文獻的研究結果顯示，光脫附量會隨著一氧化碳冰晶長冰時的溫度升高而降低。Dr. Muñoz Caro 等人 (2016) 曾嘗試將冰晶結構及自建性電場用來解釋光脫附效率的改變，然而其結果卻顯示應當還有其他的物理特徵會影響冰晶分子光脫附量隨長冰溫度變化的情況。真空紫外光子引發冰晶分子的脫附現象常使用電子躍遷所引發的脫附行為來解釋，其過程由激發態分子傳遞能量給冰晶表層的分子造成脫附。然而此模型並沒有詳細描述能量如何在冰晶分子中傳遞。本論文試著引進冰晶分子光吸收截面與隨長冰溫度變化之能量傳遞振幅與能量傳遞距離，說明一氧化碳冰晶分子之光脫附量是如何受到長冰溫度的影響。;Vacuum ultraviolet (VUV) photon induced non-thermal desorption of solid phase molecules has been applied to explain the massive amount of gas phase CO in cold dense clouds and in the interstellar region. According to previous studies, the photodesorption yield decreases with higher deposition temperatures. Muñoz Caro et al. (2016) tried to explain the change in the photodesorption yield by the structure and spontelectric field of CO ices. However, their results indicate that there are also other physical properties that affect the variation of the photodesorption yield with the deposition temperature. VUV induced photodesorption of CO ices is described as due to desorption induced by electronic transition, which is desorption caused by the transfer of energy from excited molecules to surface molecules. However, the model does not contain a detailed description of how energy transfer in CO ices occurs. In this work, we introduce an absorption cross section of CO ices, and examine how the energy amplitude and energy transfer depth vary as a function of the deposition temperature, to explain the effect of the deposition temperature on the photodesorption yield of CO ices.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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