74
T. Okutsu
In this study, we examined a method for inducing crystallization by photochemical
reaction using a method that is not directly photoexcited amino acids of proteins [11,
12]. Protein was photoexcited using light of a wavelength at which the protein does
not absorb. As a method for causing such photoexcitation, the reaction was induced
with a reaction field based on a strong light-molecule coupling field constructed
on a crystallization vessel. Proteins always have the problem of denaturation when
exposed to ultraviolet light with light absorption. In order to examine the practical
application of photoinduced crystallization, it is necessary to limit the amount of light
to be irradiated to the minimum amount necessary for nucleation. In other words,
it is necessary to carry out with as little light as possible. Excitation using a strong
photo-molecular coupling field investigated in this study is equivalent to excitation
by multiphoton absorption. Therefore, light absorption is a phenomenon that rarely
occurs and excitation efficiency is extremely low. This is the same as using extremely
weak light when excited by light absorption by one photon. The reaction field by
the strong light-molecule coupling field was constructed in a commercially available
crystallization vessel.
4.3 Reaction Field Using Light-Molecular Strong Coupling
Field
The light-molecule strong coupling field used in this study is explained [13]. The
light-molecule strong coupling field has a function of giving the influence of the
electric field of light more strongly to the molecule. In this study, localized plasmon
resonance was used as a strong light-molecule coupling field. In this field, chemical
reaction of molecules was promoted. Brus et al. predicted that the reaction would
theoretically be accelerated [14], Harris et al. reported that the aromatic photolysis
reaction was promoted near the surface of silver nanoparticles [15].
Studies on reactions using multiphoton absorption by nonlinear optical
phenomena using the electric field enhancement effect of plasmons are also
progressing. For example, it is known that simultaneous two-photon absorption
occurs when light having a high photon density. It has been also reported that
simultaneous two-photon absorption is induced even when the plasmon-enhanced
electric field by the steady light of the lamp [16, 17]. In this study, we investigated photoinduced crystallization that induces localized plasmon resonance by
multiphoton absorption of visible light using gold nanostructures.
In this study, a checkerboard-like gold nanostructure and a gold-deposited film
were used as a strong photo-molecular coupling field. Figure 4.3 shows a schematic
diagram of the gold nanostructure. The gold nanostructure is a 100 nm × 100 nm,
40 nm-high gold nanostructure island aligned on a glass substrate at intervals of
200 nm. This structure was constructed in an area of 1 mm × 1 mm by electron
beam drawing. Gold nanostructures were created in collaboration with a group of
T. Okutsu
In this study, we examined a method for inducing crystallization by photochemical
reaction using a method that is not directly photoexcited amino acids of proteins [11,
12]. Protein was photoexcited using light of a wavelength at which the protein does
not absorb. As a method for causing such photoexcitation, the reaction was induced
with a reaction field based on a strong light-molecule coupling field constructed
on a crystallization vessel. Proteins always have the problem of denaturation when
exposed to ultraviolet light with light absorption. In order to examine the practical
application of photoinduced crystallization, it is necessary to limit the amount of light
to be irradiated to the minimum amount necessary for nucleation. In other words,
it is necessary to carry out with as little light as possible. Excitation using a strong
photo-molecular coupling field investigated in this study is equivalent to excitation
by multiphoton absorption. Therefore, light absorption is a phenomenon that rarely
occurs and excitation efficiency is extremely low. This is the same as using extremely
weak light when excited by light absorption by one photon. The reaction field by
the strong light-molecule coupling field was constructed in a commercially available
crystallization vessel.
4.3 Reaction Field Using Light-Molecular Strong Coupling
Field
The light-molecule strong coupling field used in this study is explained [13]. The
light-molecule strong coupling field has a function of giving the influence of the
electric field of light more strongly to the molecule. In this study, localized plasmon
resonance was used as a strong light-molecule coupling field. In this field, chemical
reaction of molecules was promoted. Brus et al. predicted that the reaction would
theoretically be accelerated [14], Harris et al. reported that the aromatic photolysis
reaction was promoted near the surface of silver nanoparticles [15].
Studies on reactions using multiphoton absorption by nonlinear optical
phenomena using the electric field enhancement effect of plasmons are also
progressing. For example, it is known that simultaneous two-photon absorption
occurs when light having a high photon density. It has been also reported that
simultaneous two-photon absorption is induced even when the plasmon-enhanced
electric field by the steady light of the lamp [16, 17]. In this study, we investigated photoinduced crystallization that induces localized plasmon resonance by
multiphoton absorption of visible light using gold nanostructures.
In this study, a checkerboard-like gold nanostructure and a gold-deposited film
were used as a strong photo-molecular coupling field. Figure 4.3 shows a schematic
diagram of the gold nanostructure. The gold nanostructure is a 100 nm × 100 nm,
40 nm-high gold nanostructure island aligned on a glass substrate at intervals of
200 nm. This structure was constructed in an area of 1 mm × 1 mm by electron
beam drawing. Gold nanostructures were created in collaboration with a group of