Molecular nitrogen as a weak hydrogen bond acceptor is added to formic and acetic acid and their monodeuterated isotopologues. FTIR spectroscopy of supersonic expansions in the O–H stretching region reveals the formation of the weakly bound N₂–carboxylic acid complexes. Their respective spectral downshifts from the monomer fundamental vibration are used to benchmark electronic structure calculations and vibrational perturbation theory. The small size of the investigated systems allows for a wide range of electronic structure levels to be explored. The O–H stretching vibration of an open dimer of acetic acid can be discriminated from the cyclic dimer vibrations by its higher susceptibility to coexpanded nitrogen.

中文翻译：

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二氮作为亚稳态羧酸二聚体的传感器和弱氢键基准测试工具

将分子氮作为弱氢键受体添加到甲酸和乙酸及其单氘代同位素共聚物中。OH拉伸区超音速膨胀的FTIR光谱显示弱结合的N _2-羧酸配合物的形成。它们从单体基本振动中得到的频谱下移被用于基准电子结构计算和振动微扰理论。所研究系统的体积小，可以探索广泛的电子结构水平。乙酸的开放二聚体的O–H拉伸振动可以通过其对共膨胀氮的较高敏感性而与循环二聚体振动区分开。