China
Africa
Explore chapters and articles related to this topic
Langmuir-Blodgett Films
Published in Arthur T. Hubbard, The Handbook of Surface Imaging and Visualization, 2022
One of the most promising optical devices is that of the surface plasmon resonance (SPR).83 Surface plasmons are collective oscillations of the free electrons at the boundary of a metal and a dielectric. The surface plasmons are basically guided waves,83 and their resonance conditions are very sensitive to changes in the thickness and refractive index of the medium adjacent to the metal. Lloyd et al. used SPR to investigate the interaction between NOx and LB films of tetra-4-tert-butylphthalocyanine containing silicone.84 Another optical detector of toxic gases was demonstrated using fluorescent porphyrin LB films.85 They reported changes in fluorescence for NO2, HCl and Cl2 gases. The fluorescence could be quenched quantitatively in the cases of both NO2 and HCl using NH3 vapor. Oxygen could be detected using phosphorescent LB films of tetraphenyl-porphyrin palladium.86 A surface acoustic wave (SAW) oscillator incorporating LB films had a detection limit of 40 ppb NO2 in dry air.87 The subject of chemical sensors has been reviewed by Moriizumi.88
Hybrid Scanning Electrochemical Techniques
Published in Allen J. Bard, Michael V. Mirkin, Scanning Electrochemical Microscopy, 2022
Christine Kranz, Christophe Demaille
A surface plasmon is an electromagnetic wave that propagates along the surface of a metal in contact with a dielectric. Surface plasmons can thus be generated at the surface of metal electrodes in contact with an electrolyte. A configuration coupling SPR with electrochemistry typically uses a thin layer of gold (∼ 50 nm) deposited on a glass prism, as the working electrode, Figure 17.41. A polarized laser beam is directed through the prism in order to illuminate the back side of the gold/solution interface, under total reflection conditions. The intensity of the reflected light is monitored as a function of the incident angle of the laser with respect to the gold surface. At a defined angle there is coupling of the incident light with the surface plasmon modes and consequently the intensity of the reflected light decreases. Hence, the reflected intensity vs. illumination angle curve presents a very distinct minimum, whose position on the incident angle axis is extremely dependent on the local optical properties of the electrode/solution interface, Figure 17.41.
Environmental, Health, and Safety Issues of Liquid and Crystal Nanomaterials
Published in Uma Shanker, Manviri Rani, Liquid and Crystal Nanomaterials for Water Pollutants Remediation, 2022
Manviri Rani, Keshu, Uma Shanker
In many biological activities, gold nanoparticles can effectively control cellular processes. Gold nanoparticles are widely explored in photothermal therapy and drug delivery applications, as well as their light-reflecting ability, that enhance surface Plasmon resonance phenomenon. It has a great ability to bind up with thiols and amino groups for modification of drugs and other molecules (Goodman et al. 2004). But according to the publication, its toxic effect on immune dendritic cells is extracted from the bone marrow of mice. From the literature, it is revealed that gold nanoparticles with positive charge have a major impact on the toxicity of cells due to their property of easy movement from negatively charged membrane. Among cationic, anionic, and neutral counterparts of ammonium nanoparticles, cationic nanoparticles have maximum cytotoxicity. Acute and chronic administration of gold nanoparticles causes DNA damage in the cerebral cortex of the adult rat.
Sensitivity enhancement of fiber surface plasmon resonance (SPR) sensor based upon a gold film-hexagonal boron nitride—molybdenum disulfide structure
Published in Instrumentation Science & Technology, 2022
Haizhou Zheng, Jiayang Yang, Qi Wang, Bin Feng, Ruifeng An
Surface plasmon resonance refers to the phenomenon caused by the coupling between polarized light and metal surface plasmon waves, which greatly reduces the reflected light intensity at the interface between metal and medium, thus forming a resonance trough.[6–9] The position of the resonant trough changes with the refractive index (RI) of the medium.[10] When a marker in the solution binds to the sensor, the refractive index of the medium changes, causing a migration in the SPR trough that may be monitored.[5] However, due to the low photoelectric conversion efficiency, the ordinary instant plasmon resonance sensor cannot fully absorb flooded light and is unable determine small molecules and low concentrations.[11]
Phytosynthesis of silver nanoparticles from aqueous leaf extracts of Piper colubrinum: characterisation and catalytic activity
Published in Journal of Experimental Nanoscience, 2021
R. Santhoshkumar, A. Hima Parvathy, E. V. Soniya
Particle size is an integral characteristic of nanoparticles, as the reduction in the particle size leads to an increase in bioactivity and bioavailability of nanoparticles. A vast number of metallic nanoparticle preparations and synthesis methods have been described [5, 6] and involves physical and chemical methods that are widely and traditionally used for nanoparticle synthesis. The hazardous chemicals involved in the chemical synthesis of nanoparticles make it unsafe for medical usages. Some of the solid toxic chemicals used as reducing agents are non-biodegradable and are potentially harmful to the environment and biological systems [7, 8]. The green synthesis always benefits and prefers the chemical and physical synthesis in order to prevent dangerous by-products [9]. Therefore, developing capable and environment-friendly processes to synthesise silver nanoparticles is one of the most challenging tasks in nanotechnology. Silver nanoparticles are the most familiar example of redox catalysts which require less activation energy and provide a separate path to the electron transfer reaction [10]. Surface plasmon light scattering, surface plasmon resonance (SPR), surface-enhanced Rayleigh scattering, and surface-enhanced Raman scattering (SERS) characteristics of nanoparticles provide them significant benefits over bulk materials [11].
Preparation and characterization of a silver-magnesium fluoride bi-layers based fiber optic surface plasmon resonance sensor
Published in Instrumentation Science & Technology, 2020
Vicky Kapoor, Navneet K. Sharma
The optical sensing of physical and chemical parameters has been of greatest interest to the scientific community.[1–4] Surface plasmon resonance (SPR) is an optical sensing method and extremely sensitive. Surface plasmons are transverse magnetic coherent oscillations of surface charges at the interface between the metal and the dielectric.[5,6] Under resonance conditions, the consequential surface plasmon waves (SPWs) moving along the interface are excited by p-polarized incident light in a typical SPR arrangement. SPWs are transverse magnetically (TM) polarized. The electric field intensity of SPWs decays exponentially in metal and dielectric media. Because the value of propagation constant of direct light is lower than for SPWs, the direct light is unable to excite SPWs. Therefore, for exciting SPWs, the propagation constant of incident light must be increased. This goal has been accomplished with the help of a Kretschmann’s prism coupler.[7] However, prism based SPR sensing has limitations including the large size of prism, the presence of additional optical and mechanical components, and unsuitablity for remote sensing.