A full-mission analysis has been conducted of Cl-bearing species in the coma of comet 67P/Churyumov–Gerasimenko as detected by the Double Focusing Mass Spectrometer (DFMS) of Rosetta's ROSINA instrument. The isotope ratio of the two stable chlorine isotopes 37Cl/35Cl is found to be 0.336 ± 0.017, to be compared with the standard mean ocean chloride value of 0.320. The isotope ratio does not change appreciably throughout the mission. The Cl-bearing species fingerprint in DFMS indicates that there is at least one additional chlorine-bearing species in the coma next to HCl, CH3Cl, and NH4Cl. The identity of this volatile or semivolatile species is unknown at this time.

中文翻译：

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彗星 67P/Churyumov–Gerasimenko 彗发中的含氯物种和 37Cl/35Cl 同位素比

Rosetta 的 ROSINA 仪器的双聚焦质谱仪 (DFMS) 对彗发 67P/Churyumov–Gerasimenko 彗发中的含氯物种进行了全任务分析。发现两种稳定氯同位素 37Cl/35Cl 的同位素比为 0.336 ± 0.017，与标准海洋氯化物平均值 0.320 进行比较。同位素比率在整个任务期间没有明显变化。DFMS 中的含氯物种指纹表明，在昏迷中，除了 HCl、CH3Cl 和 NH4Cl 之外，至少还有一种额外的含氯物种。目前尚不清楚这种挥发性或半挥发性物种的身份。