Complete Raman spectral assignment of methanol in the C-H stretching region.
Complete Raman spectral assignment of methanol in the C-H stretching region.
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DOI：
10.1021/jp400886y
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
Yuanqin Yu;Yuxi Wang;Ke Lin;Naiyin Hu;Xiaoguo Zhou;Shilin Liu
中科院分区：
文献类型：
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作者：
Yuanqin Yu;Yuxi Wang;Ke Lin;Naiyin Hu;Xiaoguo Zhou;Shilin Liu
本文利用偏振光声拉曼光谱（PARS）研究了气态甲醇在C-H伸缩区的拉曼光谱。在退偏比测量和密度泛函理论计算的基础上，给出了一个完整的光谱归属。在~2845 cm（-1）处的谱带归属于CH 3对称伸缩振动，在~2925和~2955 cm（-1）处的谱带归属于CH 3弯曲泛音的两个费米共振模，在~2961和~3000 cm（-1）处的谱带归属于分裂CH 3反对称伸缩振动的面外和面内振动。这种归属可以澄清以往不同实验方法所造成的光谱研究的混乱，并通过液体甲醇的拉曼光谱得到证实。此外，在气态甲醇中两个反对称伸缩振动之间的39 cm（-1）大分裂归因于甲醇分子中CH 3和OH基团之间的强耦合，因为它在其他长链醇中迅速减少，如CH 3CD 2 OH。
In this work, the Raman spectrum of gaseous methanol in the C-H stretching region was investigated by polarized Photoacoustic Raman spectroscopy (PARS). On the basis of the depolarization ratio measurement and density functional theory (DFT) calculations, a complete spectral assignment has been presented. The band at ~2845 cm(-1) was assigned to CH3 symmetric stretching, the bands at ~2925 and ~2955 cm(-1) were assigned to two Fermi resonance modes of CH3 bending overtones, and the bands at ~2961 and ~3000 cm(-1) were assigned to out-of-plane and in-plane vibrations of splitting CH3 antisymmetric stretching. Such assignments can clarify the confusions among the previous spectral studies from the different experimental methods and be confirmed by the Raman spectrum of liquid methanol. Furthermore, the large splitting of 39 cm(-1) between two antisymmetric stretching in gaseous methanol was ascribed to the strong coupling between CH3 and OH groups within methanol molecule because it decreased rapidly in other long-chain alcohol, such as CH3CD2OH.