Dinu Dennis F, Oenen Kemal, Schlagin Jonas, Podewitz Maren, Grothe Hinrich, Loerting Thomas, Liedl Klaus R
Institute of Materials Chemistry, TU Wien, Getreidemarkt 9/165, Vienna 1060, Austria.
Department of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, Innsbruck 6020, Austria.
ACS Phys Chem Au. 2024 Oct 4;4(6):679-695. doi: 10.1021/acsphyschemau.4c00053. eCollection 2024 Nov 27.
Unraveling methanol's infrared spectrum has challenged spectroscopists for a century, with numerous loose ends still to be explored. We engage in this exploration based on experiments of isolating single methanol molecules in solid argon and neon matrices. We report infrared spectra of methanol in its natural isotopic composition and with partial and full deuteration. These experiments are accompanied by calculating wavenumbers involving anharmonicity and mode-coupling based on the vibrational configuration interaction approach. This allows for an unambiguous assignment of all fundamentals and resonances in the mid-infrared spectrum. An increasing degree of deuteration lifts resonances and aids in assigning bands uniquely. It also becomes evident that different notations typically used in chemistry or physics to describe molecular vibration from spectroscopy fail to describe the spectra appropriately. We highlight the shortcomings and suggest a more elaborate analysis using Sankey diagrams to unambiguously identify spectral features. Consequently, we demystify debated resonances occurring from various stretches and deformations of the methyl group.
一个世纪以来，解析甲醇的红外光谱一直是光谱学家面临的挑战，仍有许多问题有待探索。我们基于在固体氩气和氖气基质中分离单个甲醇分子的实验展开这项探索。我们报告了天然同位素组成以及部分和完全氘代的甲醇的红外光谱。这些实验还伴随着基于振动组态相互作用方法计算涉及非谐性和模式耦合的波数。这使得能够明确归属中红外光谱中的所有基频和谐振。氘代程度的增加提升了谐振，并有助于唯一地归属谱带。同样明显的是，化学或物理中通常用于从光谱学描述分子振动的不同符号无法恰当地描述光谱。我们强调了这些缺点，并建议使用桑基图进行更详细的分析以明确识别光谱特征。因此，我们揭开了由甲基的各种伸缩和变形产生的有争议的谐振之谜。
