Chapter 1
Introduction
Abstract A brief introduction of the sum frequency generation (SFG) spectroscopy, the main theme of this book, is provided. An overview of second-order
nonlinear optical processes, including SFG and second-harmonic generation (SHG),
is presented with emphasizing their spatial and temporal characteristics and symmetries. Fundamental features of visible-infrared SFG vibrational spectroscopy as
a tool of interface characterization are summarized in comparison with infrared
and Raman vibrational spectroscopies. Some examples of visible-infrared SFG
vibrational spectra are also illustrated to show typical spectroscopic information
drawn from the SFG spectroscopy.
Keywords SFG · SHG · Surface sensitivity · Vibrational spectroscopy
This chapter gives a brief introduction of the sum frequency generation (SFG)
spectroscopy, the main theme of this book, including the concept of second-order
nonlinear optical process, visible-infrared SFG spectroscopy, and some typical
experimental examples. The SFG spectroscopy has been reviewed in previous
literature from various aspects [4, 10, 18–21]. The present book deals with the theory
and computation of SFG spectroscopy, though the collaboration with experiments
will be a vital part of this book. The fundamental theory of SFG is common
to second harmonic generation (SHG). The two spectroscopies are based on the
second-order nonlinear optical processes where two photons with frequencies ω 1
and ω 2 generates a light with the sum frequency = ω 1 + ω 2 . SHG is considered
as a special case of ω 1 = ω 2 . The following theory mostly deals with SFG, while
the general discussion also holds for SHG.
1.1 Sum Frequency Generation
A material system under external electric field E induces dipole moment, or
polarization, in general. The polarization P is defined as the dipole moment per
© Springer Nature Singapore Pte Ltd. 2018
A. Morita, Theory of Sum Frequency Generation Spectroscopy,
Lecture Notes in Chemistry 97, https://doi.org/10.1007/978-981-13-1607-4_1
1
Introduction
Abstract A brief introduction of the sum frequency generation (SFG) spectroscopy, the main theme of this book, is provided. An overview of second-order
nonlinear optical processes, including SFG and second-harmonic generation (SHG),
is presented with emphasizing their spatial and temporal characteristics and symmetries. Fundamental features of visible-infrared SFG vibrational spectroscopy as
a tool of interface characterization are summarized in comparison with infrared
and Raman vibrational spectroscopies. Some examples of visible-infrared SFG
vibrational spectra are also illustrated to show typical spectroscopic information
drawn from the SFG spectroscopy.
Keywords SFG · SHG · Surface sensitivity · Vibrational spectroscopy
This chapter gives a brief introduction of the sum frequency generation (SFG)
spectroscopy, the main theme of this book, including the concept of second-order
nonlinear optical process, visible-infrared SFG spectroscopy, and some typical
experimental examples. The SFG spectroscopy has been reviewed in previous
literature from various aspects [4, 10, 18–21]. The present book deals with the theory
and computation of SFG spectroscopy, though the collaboration with experiments
will be a vital part of this book. The fundamental theory of SFG is common
to second harmonic generation (SHG). The two spectroscopies are based on the
second-order nonlinear optical processes where two photons with frequencies ω 1
and ω 2 generates a light with the sum frequency = ω 1 + ω 2 . SHG is considered
as a special case of ω 1 = ω 2 . The following theory mostly deals with SFG, while
the general discussion also holds for SHG.
1.1 Sum Frequency Generation
A material system under external electric field E induces dipole moment, or
polarization, in general. The polarization P is defined as the dipole moment per
© Springer Nature Singapore Pte Ltd. 2018
A. Morita, Theory of Sum Frequency Generation Spectroscopy,
Lecture Notes in Chemistry 97, https://doi.org/10.1007/978-981-13-1607-4_1
1