Preface
Surface-specific nonlinear spectroscopy, such as second harmonic generation (SHG)
or sum frequency generation (SFG), has been growing to be a popular tool of
interface characterization. These techniques have microscopic sensitivity to the
interfaces at a monolayer scale and are applicable to a variety of interfaces as long
as the interfaces are accessible by optical probe lights and signal. These techniques
are particularly useful to wet and/or soft interfaces, or even buried interfaces, which
are hard to be probed by most conventional surface science techniques. Therefore,
these techniques have large potential to expand our applicability of interface
characterization in wide areas of science and engineering, such as electrochemistry,
polymer science, colloid chemistry, heterogeneous atmospheric chemistry, etc. The
last decade witnessed great advances in technical aspects, and the surface nonlinear
spectroscopy is presently not just for limited experts of spectroscopy but available to
wide researchers who want to use these techniques in their fields using commercial
apparatus.
Currently I think that a major bottleneck to achieve further advancement in the
nonlinear spectroscopy lies in their difficulties to interpret the observed spectra.
Typical conventional analysis tries to interpret a spectrum by decomposing it into
some bands and by assigning these bands to various species at the interface.
However, such empirical analysis has apparently of limited utility, and spectral
decomposition is often quite ambiguous. To overcome such difficulties, therefore,
reliable support of theoretical analysis is strongly desirable in the field of surface
nonlinear spectroscopy. Recent advances in theory have made us possible to directly
“calculate” the spectra using molecular modeling and molecular dynamics (MD)
simulation, which allows for simultaneous understanding of the observed spectra
and interface structure in unprecedented details. I believe that close collaboration of
spectroscopic measurement and MD simulation will be a main avenue in the further
nonlinear spectroscopy of interfaces.
The present book aims at explaining the basic principles of theory and computation of surface nonlinear spectroscopy, mainly developed by the author’s group.
This book was originally intended to newcomers in our laboratory and in summer
vii
Surface-specific nonlinear spectroscopy, such as second harmonic generation (SHG)
or sum frequency generation (SFG), has been growing to be a popular tool of
interface characterization. These techniques have microscopic sensitivity to the
interfaces at a monolayer scale and are applicable to a variety of interfaces as long
as the interfaces are accessible by optical probe lights and signal. These techniques
are particularly useful to wet and/or soft interfaces, or even buried interfaces, which
are hard to be probed by most conventional surface science techniques. Therefore,
these techniques have large potential to expand our applicability of interface
characterization in wide areas of science and engineering, such as electrochemistry,
polymer science, colloid chemistry, heterogeneous atmospheric chemistry, etc. The
last decade witnessed great advances in technical aspects, and the surface nonlinear
spectroscopy is presently not just for limited experts of spectroscopy but available to
wide researchers who want to use these techniques in their fields using commercial
apparatus.
Currently I think that a major bottleneck to achieve further advancement in the
nonlinear spectroscopy lies in their difficulties to interpret the observed spectra.
Typical conventional analysis tries to interpret a spectrum by decomposing it into
some bands and by assigning these bands to various species at the interface.
However, such empirical analysis has apparently of limited utility, and spectral
decomposition is often quite ambiguous. To overcome such difficulties, therefore,
reliable support of theoretical analysis is strongly desirable in the field of surface
nonlinear spectroscopy. Recent advances in theory have made us possible to directly
“calculate” the spectra using molecular modeling and molecular dynamics (MD)
simulation, which allows for simultaneous understanding of the observed spectra
and interface structure in unprecedented details. I believe that close collaboration of
spectroscopic measurement and MD simulation will be a main avenue in the further
nonlinear spectroscopy of interfaces.
The present book aims at explaining the basic principles of theory and computation of surface nonlinear spectroscopy, mainly developed by the author’s group.
This book was originally intended to newcomers in our laboratory and in summer
vii