Altun Zikri, Bleda Erdi, Trindle Carl
Physics Department, Marmara University, Istanbul 34722, Turkey.
Chemistry Department, University of Virginia, Charlottesville 22902, VA, USA.
Life (Basel). 2019 Apr 23;9(2):34. doi: 10.3390/life9020034.
The production of complex molecules in ammonia-carbon dioxide ices is presumed to pass through species of formula HN:CO with further addition of ammonia and carbon dioxide. One possible landmark, carbamic acid, HNCOOH, has been implicated among the products of warming and irradiation of such ices. Experimental study of the IR spectra of residues has suggested the presence of related species, including weakly bound 1:1 and 2:1 complexes of ammonia with carbon dioxide, zwitterionic carbamic acid, ammonium carbamate, and the dimer of carbamic acid. We computed the energetics and vibrational spectra of these species as well as the complex between ammonia and carbamic acid for gas and condensed phases. By means of a new spectrum-matching scoring between computed and observed vibrational spectra, we infer species that are most probably present. The leading candidates are ammonium carbamate, the carbamic acid-ammonia complex, and the carbamic acid dimer.
在氨 - 二氧化碳冰中复杂分子的生成被认为是通过化学式为HN:CO的物种进一步添加氨和二氧化碳来实现的。一种可能的标志性物质氨基甲酸（HNCOOH），已被认为存在于此类冰升温及辐照后的产物中。对残余物红外光谱的实验研究表明存在相关物种，包括氨与二氧化碳的弱结合1:1和2:1络合物、两性离子氨基甲酸、氨基甲酸铵以及氨基甲酸二聚体。我们计算了这些物种以及气相和凝聚相中氨与氨基甲酸之间络合物的能量学和振动光谱。通过计算和观测振动光谱之间新的光谱匹配评分，我们推断出最可能存在的物种。主要候选物是氨基甲酸铵、氨基甲酸 - 氨络合物和氨基甲酸二聚体。
