262
11 Summary
simulation. In applying these formulas of χ (2) to realistic interfaces, accurate
treatment of electronic polarization and intermolecular couplings in the interface
systems are of critical importance to provide reliable interpretation of the observed
spectra. Therefore, the theory and modeling of these polarization properties were
discussed in Chaps. 5 and 6. The knowledge summarized in Chaps. 4, 5 and 6 forms
the necessary foundation of the computational analysis of SFG spectra.
Chapters 7 and 8 treat some advanced topics of SFG theory. We argued the
quadrupole contributions to the SFG and SHG processes in Chap. 7 in details, which
arise from the bulk region as well as from the interface. Chapter 8 discussed some
other topics of SFG, including the χ (3) effect and chiral applications of the SFG
spectroscopy.
The theory and principles presented in this book not only provide the formal
framework of the surface nonlinear spectroscopy, but allow us to understand
experimentally observed SFG spectra from the molecular viewpoints of electronic
properties and structure of the interfaces. Chapters 9 and 10 introduced some
applications of the computational analysis pioneered by the author’s group to aqueous and organic interfaces. These examples become prototypes of computational
analysis of SFG spectroscopy for further applications. The theoretical analysis in
combination of quantum chemical calculations and molecular dynamics simulations
is growing to become a powerful means to interpret the experimental spectra.
11.2 Future Directions
The applications of computational analysis of SFG are currently expanding, with
various modeling methods besides the CRK model [1, 4, 5, 12]. The future
computational analysis will cover a variety of interfaces treated by experimental
SFG measurement. These applications should include
• surfaces of water and aqueous solutions (water, ice, electrolyte solutions, etc.)
• liquid-liquid interfaces (water-oil, etc.)
• electrochemical interfaces (solution-electrode)
• molecules adsorbed on solid surfaces
• polymer surfaces
• Langmuir and Langmuir-Blodgett films, self-assemble monolayers
• biomolecules—cell membranes
• environmental interfaces—aerosol surface, water-mineral interface
. . .
The advance of theory is stimulated by the advance of experimental methods.
Experimental techniques of surface nonlinear spectroscopy have been remarkably
sophisticated since the first report of SFG spectrum. Just for example, the advancement of the heterodyne detected SFG provides experimental information of real
(Re[χ (2) ]) and imaginary (Im[χ (2) ]) parts of the χ (2) spectra, and allows unam-
11 Summary
simulation. In applying these formulas of χ (2) to realistic interfaces, accurate
treatment of electronic polarization and intermolecular couplings in the interface
systems are of critical importance to provide reliable interpretation of the observed
spectra. Therefore, the theory and modeling of these polarization properties were
discussed in Chaps. 5 and 6. The knowledge summarized in Chaps. 4, 5 and 6 forms
the necessary foundation of the computational analysis of SFG spectra.
Chapters 7 and 8 treat some advanced topics of SFG theory. We argued the
quadrupole contributions to the SFG and SHG processes in Chap. 7 in details, which
arise from the bulk region as well as from the interface. Chapter 8 discussed some
other topics of SFG, including the χ (3) effect and chiral applications of the SFG
spectroscopy.
The theory and principles presented in this book not only provide the formal
framework of the surface nonlinear spectroscopy, but allow us to understand
experimentally observed SFG spectra from the molecular viewpoints of electronic
properties and structure of the interfaces. Chapters 9 and 10 introduced some
applications of the computational analysis pioneered by the author’s group to aqueous and organic interfaces. These examples become prototypes of computational
analysis of SFG spectroscopy for further applications. The theoretical analysis in
combination of quantum chemical calculations and molecular dynamics simulations
is growing to become a powerful means to interpret the experimental spectra.
11.2 Future Directions
The applications of computational analysis of SFG are currently expanding, with
various modeling methods besides the CRK model [1, 4, 5, 12]. The future
computational analysis will cover a variety of interfaces treated by experimental
SFG measurement. These applications should include
• surfaces of water and aqueous solutions (water, ice, electrolyte solutions, etc.)
• liquid-liquid interfaces (water-oil, etc.)
• electrochemical interfaces (solution-electrode)
• molecules adsorbed on solid surfaces
• polymer surfaces
• Langmuir and Langmuir-Blodgett films, self-assemble monolayers
• biomolecules—cell membranes
• environmental interfaces—aerosol surface, water-mineral interface
. . .
The advance of theory is stimulated by the advance of experimental methods.
Experimental techniques of surface nonlinear spectroscopy have been remarkably
sophisticated since the first report of SFG spectrum. Just for example, the advancement of the heterodyne detected SFG provides experimental information of real
(Re[χ (2) ]) and imaginary (Im[χ (2) ]) parts of the χ (2) spectra, and allows unam-