Overlapping spectral features and new assignment of 2‐propanol in the C–H stretching region
Overlapping spectral features and new assignment of 2‐propanol in the C–H stretching region
复制标题
DOI：
10.1002/jrs.4446
复制
发表时间：
2014-03
影响因子：
2.5
通讯作者：
Yuanqin Yu;Yuxi Wang;Naiyin Hu;Ke Lin;Xiaoguo Zhou;Shilin Liu
中科院分区：
文献类型：
--
作者：
Yuanqin Yu;Yuxi Wang;Naiyin Hu;Ke Lin;Xiaoguo Zhou;Shilin Liu
利用偏振光声拉曼光谱和常规拉曼光谱分别研究了气态和液态2-丙醇在2800 ~ 3100 cm-1 C-H伸缩区的振动光谱。使用两个氘代样品，即CH 3CDOHCH 3和CD 3CHOHCD 3，CH和CH 3基团之间的重叠光谱特征进行了鉴定。借助于退偏比测量和密度泛函理论计算，给出了一个新的光谱归属。在气相中，2884 cm−1处的谱带被认为是一个CH 3费米共振模和一个CH伸缩的Gauche构象的重叠。2917和2933 cm−1处的谱带归属于另外两个CH 3费米共振模，但后者包含来自反式构象异构体CH伸缩的微弱贡献。在2950和2983 cm−1处的谱带分别归属于CH 3对称和反对称伸缩。液态异丙醇的光谱特征与气相中的光谱特征相似，只是CH的光谱带位置发生蓝移，CH 3的光谱带位置发生红移，这可能是由于液态时分子间的相互作用。这些新的归属不仅澄清了以往研究中不同光谱方法的混淆，而且为未来异丙醇的光谱应用提供了可靠的基础。版权所有© 2014约翰威利父子有限公司.
The vibrational spectra of gaseous and liquid 2-propanol in the C–H stretching region of 2800 ~ 3100 cm−1 were investigated by polarized photoacoustic Raman spectroscopy and conventional Raman spectroscopy, respectively. Using two deuterated samples, that is, CH3CDOHCH3 and CD3CHOHCD3, the overlapping spectral features between the CH and CH3 groups were identified. With the aid of depolarization ratio measurements and density functional theory calculations, a new spectral assignment was presented. In the gas phase, the band at 2884 cm−1 was assigned to the overlapping of one CH3 Fermi resonance mode and a CH stretching of gauche conformer. The bands at 2917 and 2933 cm−1 were assigned to another two CH3 Fermi resonance modes, but the latter includes weak contribution from CH stretching of trans conformer. The bands at 2950 and 2983 cm−1 were assigned to CH3 symmetric and antisymmetric stretching, respectively. The spectral features of liquid 2-propanol are similar to those in the gas phase except for the blue shift of CH and the red shift of CH3 band positions, which can be attributed to the intermolecular interaction in the liquid state. The new assignments not only clarify the confusions in previous studies from different spectral methods but also provide the reliable groundwork on spectral application of 2-propanol in the futures. Copyright © 2014 John Wiley & Sons, Ltd.