Simulation of a metallic SNOM tip illuminated by a parabolic mirror

Mihaljević, Josip; Hafner, Christian; Meixner, Alfred J.

doi:10.1364/oe.21.025926

Cited by 14 publications

(9 citation statements)

References 38 publications

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“…At 636 nm excitation, the integrated spectral intensities of individual Raman peaks are 2-4.6 times (peak to peak difference) stronger than they are for 532 nm excitation. This observation agrees well with the theoretical prediction that field enhancement at a gold tip using excitation at 636 nm is nearly 5 times higher that it is with excitation at 532 nm radiation [37].…”

Section: Electromagnetic Enhancementsupporting

confidence: 90%

“…Applying higher order laser modes in TERS has been proven advantageous. Thanks to the dominant E z 2 component in the focus of a radially polarized beam, the long axis of the tip can be effectively excited, giving rise to a strong and localized plasmonic field at the tip apex experimentally [32,35,36] and theoretically [37].…”

Section: Parabolic-mirror-assisted Optical Microscopymentioning

confidence: 99%

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Charge transfer and electromagnetic enhancement processes revealed in the SERS and TERS of a CoPc thin film

et al. 2019

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Phthalocyanines are frequently used as probing molecules in the field of single-molecule surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS). In this work, we systematically compare the SERS and TERS spectra from a thin cobalt phthalocyanine (CoPc) film that is deposited on a Au film. The contributions from electromagnetic (EM), resonance, and charge-transfer enhancements are discussed. Radially and azimuthally polarized vector beams are used to investigate the influences of molecular orientation and the localized surface plasmon resonance (SPR). Furthermore, two different excitation wavelengths (636 and 532 nm) are used to study the resonant excitation effect as well as the involvement of the charge-transfer processes between CoPc and the Au substrate. It is shown that the Raman peaks of CoPc are mostly enhanced by 636 nm excitation through a combination of resonant excitation, high EM enhancement, and chemical enhancement via charge transfer from the metal to the molecule. At 532 nm excitation, however, the SERS and TERS spectra are dominated by photoluminescence, which originates from a photo-induced charge-transfer process from the optically excited molecule to the metal. The contributions of the different enhancement mechanisms explain the optical contrasts seen in the TERS images of Au nanodisks covered by the CoPc film. The insight achieved in this work will help to understand the optical contrast in sub- or single-molecule TERS imaging and apply SERS or TERS in the field of photocatalysis.

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Section: Electromagnetic Enhancementsupporting

confidence: 90%

Section: Parabolic-mirror-assisted Optical Microscopymentioning

confidence: 99%

Charge transfer and electromagnetic enhancement processes revealed in the SERS and TERS of a CoPc thin film

et al. 2019

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“…When the sample is positioned within close proximity of the excited tip apex, the substrate material gains influence via the coupling between the oscillation field in the excited tip and its mirror image in the substrate. We have shown from previous theoretical work that the permittivity of the tip and the substrate influences the near-field enhancement at the tip apex significantly [31]. In the next set of experiments, we combined angle-resolved polarization measurements with TERS to investigate the effects of tip-sample interactions on the optical signals.…”

Section: Tip-enhanced Raman Spectroscopy Of Silicon Nanowirementioning

confidence: 99%

Revealing the local crystallinity of single silicon core-shell nanowires using tip-enhanced Raman spectroscopy

Berg¹,

Moeinian²,

Kobald³

et al. 2020

Preprint

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Tip-enhanced Raman spectroscopy is combined with polarization angle-resolved spectroscopy to investigate the nanometre-scale structural properties of core-shell silicon nanowires (crystalline Si core and amorphous Si shell), which were synthesized by platinum-catalyzed vapor-liquid-solid growth and silicon overcoating by thermal chemical vapour deposition. Local changes in the fraction of crystallinity are characterized for those silicon nanowires at an optical resolution of about 300 nm. Furthermore, we are able to resolve the variations in the intensity ratios between the crystalline Si and the amorphous Si Raman peaks by applying tip-enhanced Raman spectroscopy, at sample positions being eight nanometers apart. The local crystallinity revealed using confocal Raman spectroscopy and tip-enhanced Raman spectroscopy agree well with the high-resolution transmission electron microscopy measurements. Additionally, the polarizations of Raman scattering and the photoluminescence signal from the tip-sample nanogap are explored by combining polarization angle-resolved emission spectroscopy with tip-enhanced optical spectroscopy. Our work demonstrates the significant potential of resolving local structural properties of Si nanomaterials at the sub-10 nanometer scale using tip-enhanced Raman techniques.

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“…The development of radially polarized beams provides more choice in the selection of polarization of excitation light [39]. In the vertical plasmonic nanogap system, the performance of radially polarized beams was better than linearly polarized beams in the previous study [40][41][42][43]. Thus, the questions we need to take into consideration are whether this excitation method is applicable to the system composed of a vertical plasmonic nanocavity and 2D materials, and if radially polarized beams perform better than linearly polarized beams.…”

Section: Introductionmentioning

confidence: 98%

Plasmonic nanocavity enhanced vibration of graphene by a radially polarized optical field

Zhang

et al. 2020

Nanophotonics

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Abstract The combination of 2D materials and surface plasmon can produce some novel optical phenomena that have attracted much attention. Illuminated by light with different polarization states, the field distribution around the plasmonic structure can control the light-matter interaction. The interaction between graphene and light can be strongly enhanced by employing radially polarized beams in a nanocavity. Here, we study the selectively enhanced vibration of graphene in a coupled plasmonic gold nanocavity with a radially polarized optical field, and the coupling and enhancing mechanisms are investigated both experimentally and numerically. By focusing a radially polarized beam, a high z component of a localized near field in the nanocavity is provided to strongly enhance the interaction between graphene and light, which can be used to enhance the vibrational signal of the interlayer. For the in-plane vibration of graphene, a similar enhancement is obtained with a linearly and radially polarized optical field. A plasmonic nanocavity is used to enhance the vibration of graphene, which provides potential applications in studying the out-of-plane vibration mode and exploring the mechanism of the interlayer coupling of 2D materials.

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Simulation of a metallic SNOM tip illuminated by a parabolic mirror

Cited by 14 publications

References 38 publications

Charge transfer and electromagnetic enhancement processes revealed in the SERS and TERS of a CoPc thin film

Charge transfer and electromagnetic enhancement processes revealed in the SERS and TERS of a CoPc thin film

Revealing the local crystallinity of single silicon core-shell nanowires using tip-enhanced Raman spectroscopy

Plasmonic nanocavity enhanced vibration of graphene by a radially polarized optical field

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