Molecules, vibrational spectroscopy

Stipe B C, Rezaei M A and Flo W 1998 Single-molecule vibrational spectroscopy and microscopy Science 280 1732... 

Stipe BC, Rezaei MA, Ho W (1998) Single-molecule vibrational spectroscopy and microscopy. Science 280(5370) 1732-1735... 

How Does Single-Molecule Vibrational Spectroscopy Work .211... 

Single-molecule vibrational spectroscopy uses a measurable change in conductance across the onset for vibrational excitation of the different modes of an adsorbed molecule to identify its vibrational fingerprint. The tip of an STM is placed on the molecule and the voltage is ramped up. When the energy given to the electrons matches a quantum of vibration, the conductance changes abruptly the STM has measured the frequency of a mode of an adsorbed molecule. 

In this section, we introduce the working principle of vibrational spectroscopy. It will be compared with a parent technique called Inelastic Electron Tunneling Spectroscopy, which was developed in the 60 s. Although the working principle is similar in each of them, the specific nature of electron-vibration interaction differs. We shall conclude this section by reviewing the most important achievements of single-molecule vibrational spectroscopy. 

Ho, W. (2004) Single molecule vibrational spectroscopy with the STM. Abs. Papers Am. Chem. Soc., 227, U825. 

Vibrational spectroscopy is an important complementary tool to x-ray diffraction for stmctural characterization of materials, including supramolecular compounds. Unlike x-ray diffraction, where all the data must be collected to give the stmcture of the molecule, vibrational spectroscopy can be used to zero-in on part of the structure of interest. Furthermore, information on guest—host interactions of inclusion compounds can be readily determined from infrared (IR) and Raman spectra, whereas this information is not readily accessible from x-ray diffraction. Therefore, IR spectroscopy and more recently Raman spectroscopy are used to study the stmcture and dynamics of inclusion compounds. IR spectroscopy is also widely and routinely used to characterize supramolecular compounds containing macrocyclic molecules. The stmc-tures and dynamics of these compounds can also be studied using resonance Raman spectroscopy. 

Colaianni, S.E.M. Aubard, J. Hansen, S.H. Nielsen, O.F. Raman spectroscopic studies of some biochemically relevant molecules. Vibrational Spectroscopy 1995, 9, 111-120. 

Nafie LA, Yu G-S and Freedman TB (1995) Raman optical-activity of biological molecules. Vibrational Spectroscopy 8 231-239. 

Spectroscopies with SPMs are being developed rapidly. The ability to study isolated or small structures of adsorbates has allowed incredible insight into the rich chemistry of surfaces, particularly the defining roles that defect-sites play. The recent demonstrations of single molecule vibrational spectroscopies with the STM and NSOM have further opened up new avenues for investigation. 

W. (1999) A variable-temperature scanning tunneling microscope capable of single-molecule vibrational spectroscopy. Rev. Sci. Instrum., 70, 137-143. 

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