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K. Kneipp et al.
sion of SERS studies to the ultraviolet region, i.e. UV-SERS would offer interesting
capabilities, particularly for supporting UV resonance Raman studies in biosciences
[68, 69]. Aluminium has been considered as one of the best candidates for enhancing local fields in the UV region [70]. It has been experimentally demonstrated that
Al triangular nanoparticle arrays can support plasmon resonances that are tunable
throughout the visible and into the UV portion of the spectrum [71]. UV-SERS using
ordered Al nanohole arrays are theoretically proposed and simulated by using FDTD
method [72]. SERS spectra observed from crystal violet on aluminium using 244
nm excitation have been reported [73]. Surface-enhanced Raman scattering in the
ultraviolet spectral region was also observed on rhodium and ruthenium electrodes
[74].
Non-linear vibrational probing, such as hyper Raman spectroscopy can require
plasmonic support in very different frequency ranges since the scattering signals
appears shifted relatively to the second harmonic frequency of the excitation laser.
The problem can be addressed by using enhancing structure that exhibit plasmon
excitations over a wide spectral range. For example, silver aggregate structures can
show a broad plasmon spectrum from 400 to 1,200 nm which covers all optical fields
participating in the non-linear Raman effect [75, 76]. Another approach for dealing
with different optical frequencies in non-linear effects employs antenna elements
with different resonance wavelength matching the interacting optical fields [77].
The application of multifrequency gold nanowire antennas has been demonstrated
in frequency conversion experiments.
2.4 Selected Applications of Surface Enhanced Vibrational
Spectroscopy
2.4.1 SERS for Probing Catalytic Reactions
High molecular structural selectivity along with high detection sensitivity suggests
surface enhanced vibrational spectroscopies as powerful methods for monitoring
chemical processes and reactions.
Application of SERS for insight into catalytic processes requires bifunctional nanostructures that provide both plasmonic properties and the ability to act as catalyst.
Direct observations of catalytic reactions have been reported by using composite
nanoparticles with gold for plasmonic and Pt or Pd for catalytic function [78, 79].
In another experiment, gold nannoparticles and catalytic active Pt nanoparticles
have been simultaneous immobilization on a glass surface, see schema a in Fig. 2.6
[80]. This approach combines the advantages of easy preparation without the need
for synthesis of composite nanoparticles and high versatility regarding the choice
of catalyst. The proximity of both types of nanoparticles enables interaction of the
molecules with the platinum nanoparticles while they reside in the local optical
fields provided by the localized surface plasmons of the gold nanoparticles. The
K. Kneipp et al.
sion of SERS studies to the ultraviolet region, i.e. UV-SERS would offer interesting
capabilities, particularly for supporting UV resonance Raman studies in biosciences
[68, 69]. Aluminium has been considered as one of the best candidates for enhancing local fields in the UV region [70]. It has been experimentally demonstrated that
Al triangular nanoparticle arrays can support plasmon resonances that are tunable
throughout the visible and into the UV portion of the spectrum [71]. UV-SERS using
ordered Al nanohole arrays are theoretically proposed and simulated by using FDTD
method [72]. SERS spectra observed from crystal violet on aluminium using 244
nm excitation have been reported [73]. Surface-enhanced Raman scattering in the
ultraviolet spectral region was also observed on rhodium and ruthenium electrodes
[74].
Non-linear vibrational probing, such as hyper Raman spectroscopy can require
plasmonic support in very different frequency ranges since the scattering signals
appears shifted relatively to the second harmonic frequency of the excitation laser.
The problem can be addressed by using enhancing structure that exhibit plasmon
excitations over a wide spectral range. For example, silver aggregate structures can
show a broad plasmon spectrum from 400 to 1,200 nm which covers all optical fields
participating in the non-linear Raman effect [75, 76]. Another approach for dealing
with different optical frequencies in non-linear effects employs antenna elements
with different resonance wavelength matching the interacting optical fields [77].
The application of multifrequency gold nanowire antennas has been demonstrated
in frequency conversion experiments.
2.4 Selected Applications of Surface Enhanced Vibrational
Spectroscopy
2.4.1 SERS for Probing Catalytic Reactions
High molecular structural selectivity along with high detection sensitivity suggests
surface enhanced vibrational spectroscopies as powerful methods for monitoring
chemical processes and reactions.
Application of SERS for insight into catalytic processes requires bifunctional nanostructures that provide both plasmonic properties and the ability to act as catalyst.
Direct observations of catalytic reactions have been reported by using composite
nanoparticles with gold for plasmonic and Pt or Pd for catalytic function [78, 79].
In another experiment, gold nannoparticles and catalytic active Pt nanoparticles
have been simultaneous immobilization on a glass surface, see schema a in Fig. 2.6
[80]. This approach combines the advantages of easy preparation without the need
for synthesis of composite nanoparticles and high versatility regarding the choice
of catalyst. The proximity of both types of nanoparticles enables interaction of the
molecules with the platinum nanoparticles while they reside in the local optical
fields provided by the localized surface plasmons of the gold nanoparticles. The