The identification of the two missing conformers of gas-phase alanine: a jet-cooled Raman spectroscopy study

被引：52

作者：

Balabin, Roman M. ^{[1
]}

机构：

[1] ETH, Dept Chem & Appl Biosci, CH-8093 Zurich, Switzerland

来源：

PHYSICAL CHEMISTRY CHEMICAL PHYSICS | 2010年 / 12卷 / 23期

关键词：

SUPERSONIC JETS; GLYCINE; ACID; CONFORMATIONS; SPECTRA;

D O I：

10.1039/b924029b

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The jet-cooled spontaneous Raman spectrum of an amino acid-alanine (Ala, 2-aminopropanoic acid; H(2)NCH(CH(3))-COOH)-is reported. The low-frequency vibrational spectrum (below 500 cm(-1)) was recorded and assigned using quantum chemical data: ab initio (MP2) and DFT (BLYP, B3LYP, and PBE0). Band polarization measurements were used to confirm the vibrational assignments. The acquired medium resolution spectra (HWHM of similar to 4 cm(-1)) allow the different alanine conformations to be distinguished. Four alanine conformers were observed and identified: two previously reported by microwave spectroscopy studies and two that were previously unreported. A set of reasons for why these conformers eluded previous studies are discussed. Selective collisional relaxation processes in the jet (associated with low interconversion barriers between different alanine conformations) that depopulate the high-energy conformers were experimentally demonstrated.

引用

页码：5980 / 5982

页数：3

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