Archives June 2021

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.

News On Magneto-electric

In this days, the journal of Materials Chemistry C publishes a new paper entitled as “Magnetoelectric devices based on magnetoelectric bulk composites”

Magnetoelectric (ME) composites of bulk structures show strong ME coupling performance, and thus magnetoelectric bulk composites and their related devices have been attracting increasing attention over the last few years. Two kinds of ME coupling mechanisms can be found in ME bulk composites, i.e., direct ME coupling and converse ME coupling, where electric field control of magnetization or magnetic field control of ferroelectric polarization can be achieved. Then, ultra-fast, low-power, and miniaturized electronics can be developed based on the novel functionalities of both direct and converse ME coupling effects. Direct ME coupling is used in devices such as ME sensors and energy harvesters, while converse ME coupling is used in voltage tunable inductors, bandstop filters, ME antennas, tunable resonators, etc. Here, we present a review of bulk structure ME composite materials, as well as some notable potential applications of ME composites, with emphasis on both the opportunities and challenges for the application of ME composites. The performance of ME bulk composites, their coupling structures, state-of-the-art device applications, and perspectives on direct (magnetic to electric) and converse (electric to magnetic) ME devices are summarized.

News On Plasmonic biosensor

In this days, the Journal of Trends in Food Science & Technology publishes a new paper entitled as “Plasmonic biosensors for food control”

Food safety is becoming increasingly important because food industry must provide quality products to minimize the health risks. Traditional methods to assure food safety, such as plate count and polymerase chain reaction are accurate and robust but can hardly satisfy the needs of the food industry because they are costly and time consuming. Therefore, optical biosensors that can analyze food in a low-cost, facile, fast, sensitive, and selective manner started to emerge.

This review presents plasmonic biosensors including surface plasmon resonance (SPR), localized SPR (LSPR), fiber optic SPR (FO-SPR), surface enhanced Raman scattering (SERS), surface-enhanced fluorescence (SEF), and total internal reflection (TIR) based sensors and their applications in food pathogens monitoring. Moreover, the strengths and weaknesses of plasmonic biosensors implementation in food control are showcased.

Plasmonic biosensors could simplify procedure and radically reduce time, price and consummation of reactants, compared to traditional microbiological methods. Optical biosensors, in particular SPR, have been developed for detection of different foodborne pathogens. In parallel, analytical improvements have been achieved by coupling different techniques (fiber optics, Raman, fluorescence, luminescence) to plasmonic sensors in order to reduce the limits of detection and to improve sensitivity. The future improvements include the miniaturization of instruments to handheld devices and simplification of analysis to enable direct target detection in food matrices. Plasmonic technology can certainly have long lasting impact because the need for a simple and rapid food assay is pressing and guarantees the future development in this field.