這項研究探討了富含氮（N2）的環境中甲烷（CH4）的光化學和光物理過程，旨在了解星際冰晶和其他宇宙環境中發生的複雜化學反應。通過結合紅外光譜和四極柱質譜等量測技術，我們研究在真空紫外光（VUV）照射下CH4與N2混合冰晶中CH4的光消耗、光化學反應和光脫附。 無論CH4:N2的比例為何，CH4:N2混合冰晶中CH4的光消耗都遵循一致的趨勢，表明CH4的破壞主要由光子能量驅動，與N2濃度無關。此外，N2的存在抑制了C2H6和C3H8等碳氫化合物的形成，同時促進了HCN等含氮產物的生成。 我們的研究結果也顯示，CH4:N2混合冰晶中CH4的光脫附受到抑制，特別是在高N2濃度下。這種抑制歸因於能量從CH4優先轉移到N2分子，從而透過電子躍遷誘導脫附（DIET） 機制實現更有效的N2脫附。 這些研究結果為我們提供了關於星際冰晶光化作用的新見解，特別是有關氮氣對這些環境化學成分的影響。這些發現對於我們理解宇宙中化學反應的複雜性至關重要，並為我們探索太空中複雜分子形成的機制開啟了新的方向。 ;This study investigates the photochemical and photophysical processes of methane (CH4) in nitrogen (N2)-rich environments, aiming to understand the complex chemical reactions occurring in interstellar ices and other cosmic environments. Using a combination of experimental techniques, including infrared spectroscopy and quadrupole mass spectrometry, we studied the photodepletion, chemical reactions, and photodesorption of CH4+N2 ice mixtures under vacuum ultraviolet (VUV) irradiation. Our results reveal that the photodepletion of CH4 in CH4+N2 ice mixtures follows a consistent trend regardless of the CH4:N2 ratio, indicating that the destruction of CH4 is primarily driven by photon energy and is independent of the N2 concentration. We also found that the presence of N₂ inhibits the formation of hydrocarbons such as C2H6 and C3H8 while promoting the production of nitrogen-containing products like HCN. Our study demonstrates that CH4 desorption is suppressed in CH4+N2 ice mixtures, particularly at high N2 concentrations. This suppression is attributed to the preferential transfer of energy from CH4 to N2 molecules, leading to more efficient N2 desorption through the Desorption Induced by Electronic Transitions (DIET) mechanism. Overall, our findings provide valuable insights into the chemical complexity of interstellar ice and the role of N2 in regulating the chemical composition of these environments. These results have significant implications for astrochemistry, offering new perspectives on the formation mechanisms of complex molecules in space.
