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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Experimental Matrix Isolation Study and Quantum-Mechanics-Based Normal-Coordinate Analysis of the Anharmonic Infrared Spectrum of Picolinic Acid N-Oxide
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Experimental Matrix Isolation Study and Quantum-Mechanics-Based Normal-Coordinate Analysis of the Anharmonic Infrared Spectrum of Picolinic Acid N-Oxide

机译：吡啶甲酸N-氧化物非谐红外光谱的实验基质分离研究和基于量子力学的正坐标分析

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摘要

This work is,according to our knowledge,the first experimental matrix isolation study of a molecular system with a very short and strong intramolecular OH...O hydrogen bond.It also includes a satisfying interpretation of its entire infrared spectrum.The interpretation relies on the calculation at the DFT/B3LYP/6-31G(d,p) level of the harmonic spectrum and of the anharmonic relaxed potential energy for the stretching motion of the hydrogen-bonded proton,used with our recently modified quantum-mechanics-based normal-coordinate analysis.An important observation about the anharmonic spectrum obtained from this procedure is that the OH stretch coordinate contributes to several normal modes,mixing extensively with other in-plane internal coordinates,in particular OH-bending and C=O-stretching.The two intense normal modes with the largest contributions from the OH-stretching coordinate to the potential energy distribution and to the intensity are located near 1700 and 1500 cm~(-1).A calculated anharmonic spectrum obtained from this procedure agrees with the experimental spectrum (frequencies and intensity distribution),within the limits of the estimated uncertainties for the calculation and experiment,allowing the interpretation of the latter.The agreement for the frequencies is about 1-3%.The anharmonic spectrum calculated using the anharmonic keyword in Gaussian 03w is not in satisfactory agreement with experiment insofar as the OH-stretching mode is concerned.
机译：根据我们的知识，这项工作是对具有非常短且很强的分子内OH ... O氢键的分子系统进行的实验性基质分离研究。它还包括其整个红外光谱的令人满意的解释。在DFT / B3LYP / 6-31G（d，p）水平上计算氢键质子拉伸运动的谐波谱和非谐弛豫势能，并与我们最近基于量子力学的法线配合使用坐标分析。从此过程获得的非谐谱的一个重要观察结果是，OH拉伸坐标有助于几种正常模式，与其他平面内坐标广泛混合，特别是OH弯曲和C = O拉伸。 OH拉伸坐标对势能分布和强度的贡献最大的两个强法线模式分别位于1700和1500 cm〜（-1）附近。 d从此程序获得的非谐波频谱与实验频谱（频率和强度分布）一致，在计算和实验的估计不确定性范围内，允许对其进行解释。频率的一致性约为1-3％就OH拉伸模式而言，在高斯03w中使用非谐波关键字计算出的非谐波谱与实验并不令人满意。

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