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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Fourier transform infrared spectroscopy and theoretical study of dimethylamine dimer in the gas phase
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Fourier transform infrared spectroscopy and theoretical study of dimethylamine dimer in the gas phase

机译：气相傅里叶变换红外光谱和二甲胺二聚体的理论研究

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Dimethylamine (DMA) has been studied by gas-phase Fourier transform infrared (FTIR) spectroscopy. We have identified a spectral transition that is assigned to the DMA dimer. The IR spectra of the dimer in the gas phase are obtained by spectral subtraction of spectra recorded at different pressures. The enthalpy of hydrogen bond formation was obtained for the DMA dimer by temperature-dependence measurements. We complement the experimental results with ab initio and anharmonic local mode model calculations of monomer and dimer. Compared to the monomer, our calculations show that in the dimer the N-H bond is elongated, and the NH-stretching fundamental shifts to a lower wavenumber. More importantly, the weak NH-stretching fundamental transition has a pronounced intensity increase upon complexation. However, the first NH-stretching overtone transition is not favored by the same intensity enhancement, and we do not observe the first NH-stretching overtone of the dimer. On the basis of the measured and calculated intensity of the NH-stretching transition of the dimer, the equilibrium constant for dimerization at room temperature was determined.
机译：已经通过气相傅立叶变换红外（FTIR）光谱研究了二甲胺（DMA）。我们已经确定了分配给DMA二聚体的光谱跃迁。通过在不同压力下记录的光谱进行光谱减法获得气相中二聚体的IR光谱。通过温度依赖性测量获得了用于DMA二聚体的氢键形成的焓。我们用单体和二聚体的从头算和非谐局部模式计算来补充实验结果。与单体相比，我们的计算表明，在二聚体中，N-H键被拉长，而伸入NH的基波移至更低的波数。更重要的是，弱的NH拉伸基本跃迁在络合时具有明显的强度增加。但是，相同强度增强不支持第一个NH拉伸泛音过渡，而且我们没有观察到二聚体的第一个NH拉伸泛音。根据测得的和计算得出的二聚体的NH-拉伸转变强度，确定了室温下二聚化的平衡常数。

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