Far/Mid-Infrared Signatures of Solvent鈥揝olute Interactions in a Microhydrated Model Peptide Chain
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- 作者：Manuela Cirtog ; Anouk M. Rijs ; Yohan Loquais ; Val茅rie Brenner ; Benjamin Tardivel ; Eric Gloaguen ; Michel Mons
- 刊名：The Journal of Physical Chemistry Letters
- 出版年：2012
- 出版时间：November 15, 2012
- 年：2012
- 卷：3
- 期：22
- 页码：3307-3311
- 全文大小：300K
- 年卷期：v.3,no.22(November 15, 2012)
- ISSN：1948-7185
文摘
Far/mid-IR signatures of the first hydration step of a flexible biomolecule, the model peptide chain Ac-Phe-NH2, have been investigated in the gas phase using the selective IR/UV double-resonance laser technique. The broad spectral region investigated with the free-electron laser FELIX (150鈥?00 cm鈥?/70鈥?2 渭m) provided a direct access to three intermolecular vibrational modes of monohydrates, in which the water molecule bridges neighboring NH and CO sites of the peptide backbone. The spectral features, analyzed with the help of quantum chemistry, are assigned to the IR activity of the libration and wagging motions of the water molecule together with a strongly mode- and conformer-dependent vibrational coupling between solute and solvent molecules. These resolved spectra obtained in a so far poorly documented spectral region provide benchmark data, which should enable theoreticians of molecular interactions to assess their methods, in terms of both intermolecular potentials and treatment of the vibrational anharmonicity.