Infrared Spectroscopy of the Amide I Mode of N-Methylacetamide in Solid Hydrogen at 2鈥? K

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• 作者：Leif O. Paulson ; David T. Anderson
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：November 24, 2011
• 年：2011
• 卷：115
• 期：46
• 页码：13659-13667
• 全文大小：921K
• 年卷期：v.115,no.46(November 24, 2011)
• ISSN：1520-5207

文摘

We report high-resolution (0.05 cm^鈥?) FTIR spectra of the fundamental and first overtone of the amide I mode of trans-N-methylacetamide (NMA) trapped in solid molecular hydrogen (SMH) at cryogenic temperatures with low (0.03%) and high (55%) ortho-hydrogen (oH₂) concentrations. NMA-doped SMH samples with high oH₂ concentrations are nearly free from inhomogeneous broadening, permitting the measured amide I homogeneous line width of 1.268(8) cm^鈥? to be used to place a lower limit on the vibrational lifetime of 4.19(3) ps. Direct observation of the amide I overtone allows the harmonic vibrational frequency 蠅_e = 1726.6(5) cm^鈥? and the anharmonicity constant 蠅_ex_e = 8.5(2) cm^鈥? to be determined for NMA isolated in SMH samples with low oH₂ concentrations.