Intensity-Based Single Particle Plasmon Sensing

Abstract

Plasmon sensors respond to local changes of their surrounding environment with a shift in their resonance wavelength. This response is usually detected by measuring light scattering spectra to determine the resonance wavelength. However, single wavelength detection has become increasingly important because it simplifies the setup, increases speed, and improves statistics. Therefore, we investigated theoretically how the sensitivity toward such single wavelength scattering intensity changes depend on the material and shape of the plasmonic sensor. Surprisingly, simple equations describe this intensity sensitivity very accurately and allow us to distinguish the various contributions: Rayleigh scattering, dielectric contrast, plasmon shift, and frequency-dependent plasmon bulk damping. We find very good agreement of theoretical predictions and experimental data obtained by single particle spectroscopy.

High Quality Factor Silicon Membrane Metasurface for Intensity-Based Refractive Index Sensing

“…In Figure 3, we report the spectral response of the sensor with double NC arrays without spokes as n env changes, and we obtain a sensitivity of 170 nm/RIU. This value is much lower than in plasmonic structures and comparable with previous results obtained in dielectric platforms [19]. Although the response is linear in the range 1 ≤ n ≤ 1.01, the resonance shift is insufficient, resulting in limited sensitivity.…”

“…The NCs are made of silicon, a material endowed with a high refractive index, a crucial feature for a strong electric field confinement, and characterized by well-established nanofabrication techniques. Unlike many of the proposed sensors in literature, our device is not based on the shift of the resonant wavelength but rather on the change of reflectivity at a single wavelength [19]. In the following, we show that a single wavelength approach leads to an improved sensitivity with respect to the refractive index in the surrounding environment.…”

“…However, in an intensity-based refractive index sensor, it is possible to exploit narrow resonances even if the wavelength shift is small. In analogy to [19], we define S I as:…”

Plasmon Character Index: An Accurate and Efficient Metric for Identifying and Quantifying Plasmons in Molecules

“…Therefore, PCI can be a useful tool in identifying and quantifying plasmons and will inform the rational design of plasmonic molecules and small nanomaterials.Plasmons are collective and coherent oscillations of charge carriers driven by an external field. [1][2][3][4] They often have large optical absorbances [5][6][7] and can capture light at extreme subwavelength dimensions, 8-10 making them useful in many important applications, such as solar energy harvesting, [11][12][13][14][15] sensing, [16][17][18][19] and catalysis. [20][21][22] Plasmonic materials currently being studied are mostly nanoparticles and nanorods, whose size, shape, material composition, and other features can be easily varied to tune the optical properties of plasmons.…”

Plasmon Character Index: An Accurate and Efficient Metric for Identifying and Quantifying Plasmons in Molecules

“…Plasmons are collective and coherent oscillations of charge carriers driven by an external field. [1][2][3][4] They often have large optical absorbances [5][6][7] and can capture light at extreme subwavelength dimensions, [8][9][10] making them useful in many important applications, such as solar energy harvesting, [11][12][13][14][15] sensing, [16][17][18][19] and catalysis. [20][21][22] Plasmonic materials currently being studied are mostly nanoparticles and nanorods, whose size, shape, material composition, and other features can be easily varied to tune the optical properties of plasmons.…”