在星際介質之中，恆星與行星的孕育發生於寒冷而稠密的分子雲內。這些雲團中，氣態分子逐漸凝附於塵埃顆粒上，形成星際冰晶，如同宇宙為未來的誕生儀式悄悄鋪設的舞台。氫硫化物（H2S），即為其中一種重要的含硫成分，被認為可能是解釋「宇宙硫缺失問題」的關鍵線索。 為深入探究H2S在星際環境中的化學衍化，本研究模擬星際環境，使用1000電子伏特的電子對純H2S冰晶與H2O+H2S混合冰晶進行照射實驗。結果顯示，電子輻照會觸發H2S分子的轉化反應，生成各種硫鏈產物，包括H2S2、S3，甚至可能形成穩定的S8分子；而在富含水分子的混合冰晶中，亦觀察到氧化態硫物種的生成，如SO2與HSO4⁻等。 這些結果顯示，電子作用過程在含硫冰晶的化學轉化與耗損中具有關鍵作用，不僅改變了冰晶的組成，也可能影響硫元素在星際分子雲、原恆星環境、彗星與冰封星體表面等系統中的行蹤與分布。簡言之，硫元素可能在固相中被封存，也可能因特定條件釋出至氣相，其循環途徑正逐步浮現。 本研究為描繪宇宙中硫循環提供了重要一筆，而未來若進一步探討不同種類的輻射源與冰晶成分對反應路徑的影響，將有助於建構更為完整的星際硫化學模型，讓我們離解開宇宙的元素祕密更近一步。 ;In the interstellar medium, the formation of stars and planets occurs within cold and dense molecular clouds, where gas-phase molecules condense onto dust grains to form icy mantles. Among these, hydrogen sulfide (H2S) is considered a key sulfur-bearing species that may help resolve the long-standing issue of missing cosmic sulfur. To better understand the chemical evolution of H2S in astrophysical environments, this study investigates the effects of 1000 eV electron irradiation on pure H2S and H2O+H2S ice mixtures under simulated interstellar conditions. Electron irradiation leads to the formation of various sulfur-chain products such as H2S2, S3, and possibly S8, as well as oxidized sulfur species like SO2 and HSO4- in H₂O-rich ice mixtures. These results indicate that electron processing plays an important role in the transformation and depletion of sulfur-bearing ices, providing insights into the sulfur chemistry of dense clouds, protostars, comets, and icy planetary surfaces. This work aims to understand the pathways by which sulfur can be sequestered in solid phases or released into the gas phase in different astrophysical contexts. Future studies involving varied irradiation sources and ice compositions are suggested to further refine models of sulfur cycling in space.
