氨基酸在15-140 K辐射稳定性的原位测量
In-situ measurements of the radiation stability of amino acids at 15-140 K
摘要：
我们提出了新的动力学数据的辐射分解破坏的氨基酸原位红外光谱测量。在15，100和140 K下用0.8 MeV质子照射样品，然后在每个温度下用和不用H $_2$ O进行氨基酸衰变。观察到的辐射产物包括CO $_2$和胺，与氨基酸脱羧一致。甘氨酸、丙氨酸和苯丙氨酸的半衰期在各种地外环境中进行了估算。红外光谱的变化表明，对于所研究的每种氨基酸，在15 K时非两性结构NH $_2$ -CH $_2$（R）-COOH转化为140 K时两性结构$^+$ NH $_3$ -CH $_2$（R）-COO $^-$.
英文摘要：
We present new kinetics data on the radiolytic destruction of amino acids measured in situ with infrared spectroscopy. Samples were irradiated at 15, 100, and 140 K with 0.8-MeV protons, and amino-acid decay was followed at each temperature with and without H$_2$O present. Observed radiation products included CO$_2$ and amines, consistent with amino-acid decarboxylation. The half-lives of glycine, alanine, and phenylalanine were estimated for various extraterrestrial environments. Infrared spectral changes demonstrated the conversion from the non-zwitterion structure NH$_2$-CH$_2$(R)-COOH at 15 K to the zwitterion structure $^+$NH$_3$-CH$_2$(R)-COO$^-$ at 140 K for each amino acid studied.
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