SPR sensors for monitoring the degradation processes of Eu(dbm)3(phen) and Alq3 thin films under atmospheric and UVA exposure

Zaman

et al. 2019

Sensors

The resonant wave modes in monomodal and multimodal planar Surface Plasmon Resonance (SPR) sensors and their response to a bidimensional array of gold nanoparticles (AuNPs) are analyzed both theoretically and experimentally, to investigate the parameters that rule the correct nanoparticle counting in the emerging metal nanoparticle-amplified surface plasmon resonance (PA-SPR) spectroscopy. With numerical simulations based on the Finite Element Method (FEM), we evaluate the error performed in the determination of the surface density of nanoparticles σ when the Maxwell-Garnett effective medium theory is used for fast data processing of the SPR reflectivity curves upon nanoparticle detection. The deviation increases directly with the manifestations of non-negligible scattering cross-section of the single nanoparticle, dipole-dipole interactions between adjacent AuNPs and dipolar interactions with the metal substrate. Near field simulations show clearly the set-up of dipolar interactions when the dielectric thickness is smaller than 10 nm and confirm that the anomalous dispersion usually observed experimentally is due to the failure of the effective medium theories. Using citrate stabilized AuNPs with a nominal diameter of about 15 nm, we demonstrate experimentally that Dielectric Loaded Waveguides (DLWGs) can be used as accurate nanocounters in the range of surface density between 20 and 200 NP/µm2, opening the way to the use of PA-SPR spectroscopy on systems mimicking the physiological cell membranes on SiO2 supports.

Section: Methodsmentioning

confidence: 99%

Limits of the Effective Medium Theory in Particle Amplified Surface Plasmon Resonance Spectroscopy Biosensors

Zaman

et al. 2019

Sensors

“…UV irradiation of organic thin films may induce changes in the refractive index (cf. [17] for a recent work). Polymers containing azo dyes were first studied by Todorov and coworkers [18], who showed, since the 1980s, that anisotropy could be monitored by irradiation with polarized light.…”

Section: Azobenzene Based Polymer Layer As a Reference Samplementioning

confidence: 99%

“…2D measurement of the refractive indices of a ∼ 2 µm thick polymer layer was performed [26], taking advantage of the prism coupled modes of resonance of a waveguide (cf. [17] for a related work). 3D determination of the refractive index was also reported for Azo containing polymers with modulated polarimetry [27], a set of three probe lasers [28], a combination of ellipsometry techniques [29] and waveguide spectroscopy [13].…”

Section: Thickness Estimation and Comparison With Afm Measurementsmentioning

confidence: 99%

Thickness determination in anisotropic media with plasmon waveguide resonance imaging

Harté¹,

Alves²,

Ihrke³

et al. 2019

Opt. Express

This paper describes a simple procedure to determine the local thickness of a thin anisotropic layer. It also discriminates between isotropic and anisotropic regions, provided a smoothness hypothesis on the refractive index distribution is satisfied. The procedure is based on the analysis of surface plasmon resonance (SPR) data acquired in an imaging mode. The general arrangement of the setup is the Kretschmann configuration. We show, on an azobenzene modified polymer layer, good agreement between atomic force microscopy and optical measurements of thickness variation.

“…We also want to explore the potentialities of SPR spectroscopy in the monitoring of the degradation processes of organic luminescent thin films, with the aim to develop organic material based SPR-UVA dosimeter in the Surface Plasmon Coupled Emission configuration [46].…”

Section: Objectivesmentioning

confidence: 99%

“…The nominal thickness of the organic thin films was 30 nm. The temperature was maintained at approximately 23 °C with a humidity of 50% [46]…”

mentioning

confidence: 99%

Surface Plasmon Resonance Spectroscopy for the Characterization of Nanoparticles, Organic Thin Film and 2-D Materials

ZAMAN¹

Studying and carrying out high level scientific research was a great honor for me and I am very grateful to all of peoples who have helped me a lot with their guidance, knowledge, assistance and patience. I am deeply thankful to my supervisor Tommaso Del Rosso who is incredibly smart, good and very kind person. It is his trust and motivation from beginning to end that enables me to focus my mind and efforts on my research.