Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation

• Guoke Wei,
• Jinliang Wang and
• Yu Chen

Beilstein J. Nanotechnol. 2015, 6, 686–696, doi:10.3762/bjnano.6.69

• The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e

• nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance. Keywords: discrete dipole approximation (DDA); enhancement factor; near-field; silver nanorod array; surface-enhanced Raman scattering (SERS); Introduction Surface-enhanced

• dielectric constants of Ag were obtained from the experimental data of Johnson and Christy [24]. The value of the interaction cut-off parameter γ was taken to be 0.01. Electromagnetic enhancement factor The electromagnetic enhancement factor (EF) is commonly approximated by the following formula [25]: where

Hollow plasmonic antennas for broadband SERS spectroscopy

• Gabriele C. Messina,
• Mario Malerba,
• Pierfrancesco Zilio,
• Ermanno Miele,
• Michele Dipalo,
• Lorenzo Ferrara and
• Francesco De Angelis

Beilstein J. Nanotechnol. 2015, 6, 492–498, doi:10.3762/bjnano.6.50

• comes from the tip of the antenna and this can be attributed to the presence of the hotspot reported in Figure 3. In order to quantify the enhancement factor, we compared the Raman signal from the tip of an antenna with the signal coming from the surrounding silver substrate. Figure 5 reports the Raman

• the antenna tip to act as field enhancer. By taking into account the difference in laser power, integration time, signal counts, and number of scattering centers (hotspot area ≈103 nm2, laser beam spot ≈2 × 106 nm2) the estimated field enhancement factor of 60 was obtained. We remark that this value

Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

• Jes Ærøe Hyllested,
• Marta Espina Palanco,
• Nicolai Hagen,
• Klaus Bo Mogensen and
• Katrin Kneipp

Beilstein J. Nanotechnol. 2015, 6, 293–299, doi:10.3762/bjnano.6.27

• . The capability of green silver nanoparticles for enhancing Raman signals in SERS was tested by using NIR excitation and the non-resonant target molecule para-mercaptobenzoic acid (pMBA). Figure 2b shows a SERS spectrum of pMBA. The enhancement factor was inferred from a comparison with the normal

Localized surface plasmon resonances in nanostructures to enhance nonlinear vibrational spectroscopies: towards an astonishing molecular sensitivity

• Dan Lis and
• Francesca Cecchet

Beilstein J. Nanotechnol. 2014, 5, 2275–2292, doi:10.3762/bjnano.5.237

• intensity is proportional to |g|²·|E0|² = |g|²·I0, the specific case in which both the incident and scattered fields are in resonance with a (broad) plasmon mode makes the SERS intensity to scale up with |g|4·I0, leading to an enhancement factor of 1012. Accordingly, LSPR represents the most commonly used

• only a limited fraction of the chemisorbed molecules was precisely located at the nanosphere junctions, thereby estimating the local enhancement factor to range from 104 to 106. It is interesting to notice that for both gold and silver coating, the SFG vibrational modes appeared as clear peaks when

• , optimizing the enhancement factor would require both the visible and SFG fields to match the plasmon resonance, simultaneously. In a SFG experiment, this is difficult since the commonly used nanostructures possess rather narrow LSPR modes, which indeed promotes multi-frequency resonances. However, the use of

Properties of plasmonic arrays produced by pulsed-laser nanostructuring of thin Au films

• Katarzyna Grochowska,
• Katarzyna Siuzdak,
• Peter A. Atanasov,
• Carla Bittencourt,
• Anna Dikovska,
• Nikolay N. Nedyalkov and
• Gerard Śliwiński

Beilstein J. Nanotechnol. 2014, 5, 2102–2112, doi:10.3762/bjnano.5.219

• enhancement in the mid-field, and the far-field resonant response observed via the SPR spectrum. The enhancement factor (EF) can be estimated from relation [48]: where ISERS and IR are intensities of SERS and Raman signals, and NR and NSERS are the number of molecules contributing to Raman and SERS

• 514 nm (Figure 6a). Thus, the cross section for non-resonant SERS signal is on the order of ≈10−19–10−20 cm2 which corresponds to the enhancement factor of about 1010. For the semi-regular (random) structures, the reported average values of the EF lie in the range of 101–103 for non-optimized

The optimal shape of elastomer mushroom-like fibers for high and robust adhesion

• Burak Aksak,
• Korhan Sahin and
• Metin Sitti

Beilstein J. Nanotechnol. 2014, 5, 630–638, doi:10.3762/bjnano.5.74

• increase. Reported values are approximate pull-off loads near saturation as interpreted from the graphical data presented in [21]. Let us define an enhancement factor e as the ratio of the pull-off load between two different fiber arrays. For an experiment that uses hemispherical glass indenter with a

• radius much larger than the dimensions of an individual fiber in the array, the enhancement factor of mushroom-like fibers over the cylindrical fibers with the same packing density, stalk radius, height, and material becomes Here, Pm and Pc are the pull-off loads for the mushroom-like and cylindrical

Probing the plasmonic near-field by one- and two-photon excited surface enhanced Raman scattering

• Katrin Kneipp and
• Harald Kneipp

Beilstein J. Nanotechnol. 2013, 4, 834–842, doi:10.3762/bjnano.4.94

• -field of nanoaggregates. Here we infer the enhancement factor for the near-field in the hottest hot spots by considering the anti-Stokes to Stokes signal ratios during surface-enhanced pumped anti-Stokes Raman scattering (SEPARS) experiments as well as the ratios between two- and one-photon excited

• field enhancement factor A(ν) to the power of six, because of its quadratic dependence on the excitation intensity [44][45]. This different dependence allows to infer the field enhancement Eloc2/E02 in the hot spots of the nanoaggregates from the ratio between their one- and their two-photon excited

• only 0.00003 % of the surface of the nanoaggregates provide electromagnetic SERS enhancement factors on the order of 1012. For more regular Ag films over nanospheres (AgFON) substrates, it has been found that 0.0003% of the surface provides an enhancement factor larger than 1010 [49] and 0.003% exhibit

Mapping of plasmonic resonances in nanotriangles

• Simon Dickreuter,
• Julia Gleixner,
• Andreas Kolloch,
• Johannes Boneberg,
• Elke Scheer and
• Paul Leiderer

Beilstein J. Nanotechnol. 2013, 4, 588–602, doi:10.3762/bjnano.4.66

• profile of the laser is of vital importance: To gain insight into more than the distribution of the near-field enhancement of a nanoscale object, the absolute enhancement factor has to be measured. In near-field photography, this is commonly done by comparing the threshold of the imaging mechanism (e.g

• measurements. Above a certain incident local fluence I(x), however, which we denote as , an ablation of the substrate's surface is visible. (The asterisk indicates that is smaller than the ablation threshold of the bare substrate, Ith,abl, due to the local field enhancement factor FE: ·FE = Ith,abl). The

• intensity enhancement factor is about 10, a factor of two to five below the results of the simulations in Figure 6a and Figure 12 (shown below). Shape dependence To demonstrate the dependence of both field distribution and field enhancement on the details of the shape of a nanostructure, two similar types

Femtosecond-resolved ablation dynamics of Si in the near field of a small dielectric particle

• Paul Kühler,
• Daniel Puerto,
• Mario Mosbacher,
• Paul Leiderer,
• Francisco Javier Garcia de Abajo,
• Jan Siegel and
• Javier Solis

Beilstein J. Nanotechnol. 2013, 4, 501–509, doi:10.3762/bjnano.4.59

• particle, illuminated at oblique incidence by a laser with a wavelength of 800 nm. The intensity distribution shows a bright spot corresponding to an enhancement factor of the order of 40, evidencing that in a first approach the particle (with a Mie parameter ka ≈ 40, where a is the particle radius and k

• illuminated at a wavelength of 800 nm and at an angle of 54°. The position of the particle is shown as a semitransparent circle. The spatial intensity distribution has been normalized to the incoming beam intensity (I0). (b) Same as (a) but re-scaling the color scale to a maximum enhancement factor (I/I0) of

A nano-graphite cold cathode for an energy-efficient cathodoluminescent light source

• Alexander N. Obraztsov,
• Victor I. Kleshch and
• Elena A. Smolnikova

Beilstein J. Nanotechnol. 2013, 4, 493–500, doi:10.3762/bjnano.4.58

• , radius of emission area r, L is the distance between two emission sites which is supposed to be in the same order as the height h, and β is the so-called field enhancement factor which may be estimated as the aspect ratio r/h. Thus, the expected range for the averaged emission current density of a

Near-field effects and energy transfer in hybrid metal-oxide nanostructures

• Ulrich Herr,
• Barat Achinuq,
• Cahit Benel,
• Giorgos Papageorgiou,
• Manuel Goncalves,
• Johannes Boneberg,
• Paul Leiderer,
• Paul Ziemann,
• Peter Marek and
• Horst Hahn

Beilstein J. Nanotechnol. 2013, 4, 306–317, doi:10.3762/bjnano.4.34

• module, which solves the Maxwell equations in the frequency domain based on the finite-element method. Bowtie model antenna structures have been defined with geometries close to the experimental ones. The aim was to calculate the relative electrical field enhancement factor E/E0 of the local field

• strength E over the field of the incident light wave E0. Dielectric properties of Ag have been taken from the literature [18]. As an example, Figure 11 shows the field-enhancement factor in the center of the gap between two triangles of a bowtie nanoantenna structure made of a 30 nm thick Ag layer for two

• triangle to the centre of the opposing base) is 100 nm. Resonances are found, which depend on the size of the antenna but also on the dielectric constants of the environment (substrate and cover layer). The spatial distribution of the enhancement factor in the region of the maximum (around 700 nm) for

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94