News On Metasurface for photocatalyst enhancement

In this days, the Journal of Nano select publishes a new paper entitled as “Two-dimensional photonic metasurfaces for slow light-controlled photocatalysis”

Photocatalysis using semiconductor materials like titania (TiO2) is a key method for environmental purification or solar fuel generation. Nanostructures that maximize incident light absorption are highly desired to enhance depollution rate or solar-to-fuel conversion efficiency in limited volumes of catalysts. Here, we report on structural and optical properties of metasurfaces based on a 20 nm thick anatase layer conformally deposited onto a wavelength-scale two-dimensional periodic photonic lattice. We investigate the NO degradation using such metasurfaces, and evaluate the impact of the patterning on photocatalytic activities between 340 and 400 nm. In the 380–385 nm range, the mean photochemical efficiency is increased by a factor up to 5.7 compared to flat references, with an overall three-fold enhancement within the whole spectral range of interest. This approach can be applied to numerous types of systems by varying active materials, leading to substantial improvements in air/water depollution, water splitting or artificial photosynthesis processes.

News On Quantum Plasmonics

In this days, the journal of Advanced Materials publishes a new paper entitled as “Quantum Plasmonics: Energy Transport Through Plasmonic Gap”

At the interfaces of metal and dielectric materials, strong light–matter interactions excite surface plasmons; this allows electromagnetic field confinement and enhancement on the sub-wavelength scale. Such phenomena have attracted considerable interest in the field of exotic material-based nanophotonic research, with potential applications including nonlinear spectroscopies, information processing, single-molecule sensing, organic-molecule devices, and plasmon chemistry. These innovative plasmonics-based technologies can meet the ever-increasing demands for speed and capacity in nanoscale devices, offering ultrasensitive detection capabilities and low-power operations. Size scaling from the nanometer to sub-nanometer ranges is consistently researched; as a result, the quantum behavior of localized surface plasmons, as well as those of matter, nonlocality, and quantum electron tunneling is investigated using an innovative nanofabrication and chemical functionalization approach, thereby opening a new era of quantum plasmonics. This new field enables the ultimate miniaturization of photonic components and provides extreme limits on light–matter interactions, permitting energy transport across the extremely small plasmonic gap. In this review, a comprehensive overview of the recent developments of quantum plasmonic resonators with particular focus on novel materials is presented. By exploring the novel gap materials in quantum regime, the potential quantum technology applications are also searched for and mapped out.

Congratulation for our new paper in Scientific Reports

Detection of Scorpion Venom by Optical Circular Dichroism Method

Y. Mazhdi, S. M. Hamidi

Various efforts have been made to detect minimum amounts of any toxic materials in water or the neurotoxic effect of venom (Odontobuthus Doriae Scorpion) in the humans҆ blood serum nerve by high-sensitivity, accurate, and low-cost sensors in order to enhance life style. Therefore, the present study was done to investigate reliability of two-dimensional plasmonic structure and circular dichroism (CD) in toxic samples in order to measure and determine venom concentrations and its neurotoxic effect on humans҆ blood serum Neurotransmitter analytes. Our results confirmed dependency of CD signal to neurotoxic effect of venom concentrations and good sensitivity of this sensor with the help of achiral plasmonic structure.

Congratulations for Our new paper in Journal of Physica Scirpta

Random laser action in the visible region by dye-based sliver Nano-hexagonal colloid media

R. A. Ejbarah, J. M. Jassim, H. Yazdanfar, S. M. Hamidi

In our attempt to reduce the threshold for dye-based random lasers, a new kind of random lasing media is demonstrated based on silver nano-hexagonal as scattering centers. For this purpose, we use a chemical method to synthesize nano hexagonal silver scatterer points and dissolve them in polymer and Rhodamine B dye media in different concentrations and different sizes. Our results from these samples under different pumping power, confirm the strong dependence on the sizes and concentration on the transition from incoherent to the coherent random laser, which is starts from 0.061 MW/cm² as threshold power. This threshold power and linewidths of emission peaks decrease by an increase in the size and concentrations of nano-hexagonal points to 0.04 MW/cm² and 0.2 nm, respectively.

News On Plasmonics

Journal of Sensors publishes a paper entitled as “Plasmonics for Telecommunications Applications”

Abstract: Plasmonic materials, when properly illuminated with visible or near-infrared wavelengths, exhibit unique and interesting features that can be exploited for tailoring and tuning the light radiation and propagation properties at nanoscale dimensions. A variety of plasmonic heterostructures have been demonstrated for optical-signal filtering, transmission, detection, transportation, and modulation. In this review, state-of-the-art plasmonic structures used for telecommunications applications are summarized. In doing so, we discuss their distinctive roles on multiple approaches including beam steering, guiding, filtering, modulation, switching, and detection, which are all of prime importance for the development of the sixth generation (6G) cellular networks.

News On Bio-Photonics

The Journal of Sensors and Actuators B: Chemical published a paper entitled as “Surface plasmon resonance biosensor for enzyme-free amplified microRNA detection based on gold nanoparticles and DNA super sandwich”

A novel enzyme-free amplified surface plasmon resonance (SPR) biosensor for microRNA (miRNA) detection was developed based on gold nanoparticles (AuNPs) coupled with DNA supersandwich. In the detection strategy, the DNA-linked AuNPs as the primary amplification element, not only hybridized with the capture DNA on the Au film to amplify SPR signal but also initiated the subsequent secondary amplification, i.e. DNA supersandwich formation of two report probes. In the presence of target, stem–loop structure of capture DNA on the Au film surface was unfolded, and DNA-linked AuNPs were bound to Au film by hybridization with terminus of capture DNA. Then, the carried assistant DNA on the AuNPs could trigger an alternative hybridization reaction of two report probes, resulting in the formation of DNA supersandwich. Due to the electronic coupling between localized plasmon of AuNPs and the surface plasmon wave associated with Au film, as well as the enhancement of the refractive index of the medium next to the metal film caused by DNA supersandwich structure, the shift of resonance angle was enhanced obviously. By employing the enzyme-free dual signal amplification strategies, as low as ca. 8 fM miRNA-21 could be detected. Moreover, this assay also showed high selectivity toward single-base mismatch, and demonstrated its applicability for the target detection in human serum. This work may provide great potential applications in future clinical analysis.

Congratulations for Our New Paper in Waves in Random and Complex Media

Two-dimensional plasmonic multilayer as an efficient tool for low power random lasing applications

Saddam F. Haddawi, Hammad R. Humud, Sakineh Almasi Monfared & S. M. Hamidi

Multi wavelength lasing is desired in two-dimensional flexible plexcitonic nanostructures through surface lattice plasmon amplification. For this purpose, gold nano-rods covered by the gold dispersed Rhodamine B was used as the first gain media. Then, the spacer layer by Poly-Vinyl-Pyrrolidone polymer was implemented to enhance the total internal reflection between polydimethylsiloxane substrate and this polymer. Finally, it was coated by methylene Blue dye with three different gold concentrations as the second gain media. To achieve multi-wavelength random laser, these three layers pumped by nanosecond green laser and the lasing were collected by spectrometer due to band edge lattice plasmons in the arrays of plasmonic nano rods in a homogeneous environment. Based on the results, narrow emission peaks were emerged with a full width at half maximum less than 2nm for every wavelength region, and threshold lasing reduced to the minimum value, along with the maximum emission intensity of multi-wavelength region.

News On Photocatalysis

In this days, the journal of Nano Research published a new paper entitled as “Helium droplet assisted synthesis of plasmonic Ag@ZnO core@shell nanoparticles”

Plasmonic Ag@ZnO core@shell nanoparticles are formed by synthesis inside helium droplets with subsequent deposition and controlled oxidation. The particle size and shape can be controlled from spherical sub-10 nm particles to larger elongated structures. An advantage of the method is the complete absence of solvents, precursors, and other chemical agents. The obtained particle morphology and elemental composition have been analyzed by scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS). The results reveal that the produced particles form a closed and homogeneous ZnO layer around a 2–3 nm Ag core with a uniform thickness of (1.33 ± 0.15) nm and (1.63 ± 0.31) nm for spherical and wire-like particles, respectively. The results are supported by ultraviolet photoelectron spectroscopy (UPS), which indicates a fully oxidized shell layer for the particles studied by STEM. The plasmonic properties of the produced spherical Ag@ZnO core@shell particles are investigated by two-photon photoelectron (2PPE) spectroscopy. Upon excitation of the localized surface plasmon resonance in Ag at around 3 eV, plasmonic enhancement leads to the liberation of electrons with high kinetic energy. This is observed for both Ag and Ag@ZnO particles, showing that even if a Ag cluster is covered by the ZnO layer, a plasmonic enhancement can be observed by photoelectron spectroscopy.

Congratulations for our new paper in journal of Optical and Quantum electronics

One dimensional efficient photocatalyst based on plasmonic grating

Y. AlIssa, S. M. Hamidi*, A. Shahnazi, M. R. Nabid

We can summarize the benefits of the water photocatalysis by two words: clean energy and purification of pollutants, and its problems as the large energy gap and electron-hole recombination. Scientists are still looking for a semiconductor whose energy gap lies in the visible region, with electron-hole pairs of longer life time. One of the proposed solutions in this field is combining the available semiconductors (such as TiO₂) with a metal of plasmonic properties. The existing of the plasmonic metal will ensure that the visible portion of the solar region will involve in the photocatalysis action. It will be absorbed by the plasmonic metal, be transformed into a local energy that leads to excitation processes in the semiconductor. Also, the existing of the metal will guarantee a longer life time for the electron-gap pairs generated in the semiconductor, as the metal acts as a sink for the electrons generated in the semiconductor. In this paper, we created a unique photocatalyst based on one dimensional grating coated by gold thin film and covered by TiO₂ cap layer. By examining the sample with visible radiation, we obtained a rate of sabotage of 25 percent within three hours.

Congratulations for our new paper in the European Physical Journal Plus

Role of Plasmonics in Detection of Deadliest Viruses: a Review

Foozieh Sohrabi, Sajede Saeidifard, Masih Ghasemi, Tannaz Asadishad, Seyedeh Mehri Hamidi*, Seyed Masoud Hosseini

Viruses have threatened animal and human lives since a long time ago all over the world. Some of these tiny particles have caused disastrous pandemics that killed a large number of people with subsequent economic downturns. In addition, the quarantine situation itself encounters the challenges like the deficiency in the online educational system, psychiatric problems and poor international relations. Although viruses have a rather simple protein structure, they have structural heterogeneity with a high tendency to mutation that impedes their study. On top of the breadth of such worldwide worrying issues, there are profound scientific gaps, and several unanswered questions, like lack of vaccines or antivirals to combat these pathogens. Various detection techniques like the nucleic acid test, immunoassay, and microscopy have been developed; however, there is a tradeoff between their advantages and disadvantages like safety in sample collecting, invasiveness, sensitivity, response time, etc. One of the highly-resolved techniques that can provide early-stage detection with fast experiment duration is plasmonics. This optical technique has the capability to detect viral proteins and genomes at the early-stage via highly-sensitive interaction between the biological target and the plasmonic chip. The efficiency of this technique could be proved using commercialized techniques like reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) techniques.  In this study, we aim to review the role of plasmonic technique in the detection of 11 deadliest viruses besides 2 common genital viruses for the human being. This is a rapidly moving topic of research, and a review article that encompasses the current findings may be useful for guiding strategies to deal with the pandemics. By investigating the potential aspects of this technique, we hope that this study could open new avenues toward the application of point-of-care techniques for virus detection at early-stage that may inhibit the progressively hygienic threats.