1 Introduction to Laser Micro-to-Nano Manufacturing
11
1.3.2 Surface Plasmonic Excitation of Nanoparticles
Surface Plasmons are coherent and collective electron oscillations bounded at the
interface between two materials with positive and negative real part of dielectric
functions respectively [24]. Fig. 1.5 shows the local electrical filed enhancement due
to surface plasmonic excitation. The inherent subwavelength nature of surface plasmons enables significant spatial confinement of light energy and thereby dramatically
strengthen the interaction between photons and materials. [56, 57] The enhanced
light–matter interactions create fast-developing fields on plasmon-enhanced Raman
spectroscopy [58, 59], photocatalysis [60], photothermal [61, 62], photovoltaic [63],
fluorescence [64], nonlinear optics [65], etc.
The interaction of plasmonic material with light can be generally regard as the
interaction of photons with the free electron gas inside the materials. Over a wide
frequency range, the optical properties of plasmonic material can be linked to the
well-known Drude approximation [66], where a gas of free electrons of number
density moves against a fixed background of positive ion cores [24]. Here, electronelectron interactions and details of the lattice potential are simplified by using the
effective mass of the electrons instead, under the hypothesis that the band structure is
incorporated into the effective mass in some certain degree. The electrons oscillates
with the applied light at an angular frequency ω, and their motion is damped via
the relaxation time of the free electron gas τ. The dielectric function of plasmonic
material can be write as
Fig. 1.5 The field distributions of localized surface plasmon resonances (LSPRs) in gold
nanospheres and nanoplates
11
1.3.2 Surface Plasmonic Excitation of Nanoparticles
Surface Plasmons are coherent and collective electron oscillations bounded at the
interface between two materials with positive and negative real part of dielectric
functions respectively [24]. Fig. 1.5 shows the local electrical filed enhancement due
to surface plasmonic excitation. The inherent subwavelength nature of surface plasmons enables significant spatial confinement of light energy and thereby dramatically
strengthen the interaction between photons and materials. [56, 57] The enhanced
light–matter interactions create fast-developing fields on plasmon-enhanced Raman
spectroscopy [58, 59], photocatalysis [60], photothermal [61, 62], photovoltaic [63],
fluorescence [64], nonlinear optics [65], etc.
The interaction of plasmonic material with light can be generally regard as the
interaction of photons with the free electron gas inside the materials. Over a wide
frequency range, the optical properties of plasmonic material can be linked to the
well-known Drude approximation [66], where a gas of free electrons of number
density moves against a fixed background of positive ion cores [24]. Here, electronelectron interactions and details of the lattice potential are simplified by using the
effective mass of the electrons instead, under the hypothesis that the band structure is
incorporated into the effective mass in some certain degree. The electrons oscillates
with the applied light at an angular frequency ω, and their motion is damped via
the relaxation time of the free electron gas τ. The dielectric function of plasmonic
material can be write as
Fig. 1.5 The field distributions of localized surface plasmon resonances (LSPRs) in gold
nanospheres and nanoplates