2013/01/19 by Satoshi Nihonyanagi, Jahur A. Mondal, S. Yamaguchi +2 · 11 citations
Physics and Astronomy · Chemistry · Biochemistry, Genetics and Molecular Biology · #Spectroscopy and Quantum Chemical Studies #Molecular spectroscopy and chirality #Photosynthetic Processes and Mechanisms
paper · doi:10.1146/annurev-physchem-040412-110138
Vibrational sum-frequency generation (VSFG) spectroscopy is a powerful tool to study interfaces. Recently, multiplex heterodyne-detected VSFG (HD-VSFG) has been developed, which enables the direct measurement of complex second-order nonlinear susceptibility [χ((2))]. HD-VSFG has remarkable advantages over conventional VSFG. For example, the imaginary part of χ((2)) [Imχ((2))] obtained with this interferometric technique is the direct counterpart to the infrared [Imχ((1))] and Raman [Imχ((3))] spectra in the bulk, and it is free from the spectral deformation inevitable in conventional VSFG [|χ((2))|(2)] spectra. The Imχ((2)) signal is obtained with a sign that contains unambiguous information about the up/down orientation of interfacial molecules. Furthermore, HD-VSFG can be straightforwardly extended to time-resolved measurements when combined with photoexcitation. In this review, we describe the present status of experiments and applications of multiplex HD-VSFG spectroscopy, in particular with regard to the orientation and structure of interfacial water at charged, neutral, and biorelevant water interfaces.