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Hydrothermal transforming phase structure and chemical composition of V2O5 for elevating electrochemical property of zinc ion batteries
(2024-05-01)
Triosod, Sureerat
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Phakkhawan, Authit
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Phumuen, Phatcharin
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Wanabut, Wassana
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Chanlek, Narong
V<inf>2</inf>O<inf>5</inf> was hydrothermally modified in NaOH or KOH solutions at 180 °C for 24 h. The NaOH-modified powders had a nanorod-like structure with a crystal structure matching Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O. The TG/DTA results of Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O powders show a mass reduction of 4.24 % at 300 °C, corresponding to n of 1.496. KOH-modified powders have large rods and irregular structures with a crystal structure matching KV<inf>3</inf>O<inf>8</inf>. Its TG/DTA spectrum shows a very small percentage change, just 0.37 % at 600 °C. Cyclic voltammetry (CV) curves of a Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O cathode in a 2 M ZnSO<inf>4</inf> electrolyte exhibit higher oxidation and reduction current densities than those of pure V<inf>2</inf>O<inf>5</inf> and KV<inf>3</inf>O<inf>8</inf> electrodes.The best capacity of a Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O electrode is 296.10 mAh g-1 at a current density of 50 mA g−1, which is higher than those of pure V<inf>2</inf>O<inf>5</inf> (102.90 mAh g-1) and KV<inf>3</inf>O<inf>8</inf> (91.07 mAh g-1) electrodes. EDS and XPS results reveal that the charge and discharge states involve de-insertion and insertion of Zn2+ ions out of/into the electrodes. Computational analysis of Zn intercalation into V<inf>2</inf>O<inf>5</inf>, Na<inf>2</inf>V<inf>6</inf>O<inf>16</inf>·nH<inf>2</inf>O, and KV<inf>3</inf>O<inf>8</inf> structures displays increasing electron density on neighboring V atoms, which explains the increasing V4+/V5+ ratio in the discharged state as evidenced by XPS spectra.
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Evaluating Noise Reduction Methods for Raman Spectroscopy in Transmission and Reflection Configurations
(2024-05-01)
Sassuvun, Wasunun
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Buranasiri, Prathan
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Wicharn, Surawut
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Puttharugsa, Chokchai
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Limnonthakul, Puenisara
This work involved comparing Raman signals obtained from two different Raman spectroscopy configurations, using two distinct noise reduction methods. The excitation light source was a laser diode with a wavelength of 532 nm. A long-pass filter and focusing lens were utilized to block the excited light from the source and concentrate the Raman signals due to their weaker nature compared to the excited light signals. Light of 532 nm wavelength was blocked during green laser diode illumination using a long-pass filter. Two configurations were studied: transmission Raman spectroscopy (TRS) and reflection Raman spectroscopy (RRS). Raman signals from both configurations were compared, and the boxcar averaging and Vancouver Raman algorithm (VRA) noise reduction methods were investigated and compared. The results showed that Raman signals from the transmission configuration were higher than those from the reflection configuration, and noise signals were effectively reduced using both the boxcar averaging and VRA methods.
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Recursive-formula for second-harmonic generation problem in photonic hypercrystal
(2022-09-01)
Buranasiri, Prathan
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Plaipichit, Suwan
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Puttharugsa, Chokchai
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Wicharn, Surawut
In this work, we proposed a recursive-formula based on transfer-matrix method to solve problem of second-harmonic generation by obliquely incident fundamental-harmonic wave in a photonic hypercrystal, which is composed of one-dimensional periodically alternating arrangement of nonlinear hyperbolic metamaterial layer with anisotropic permittivities: ε<inf>axx</inf>, ε<inf>azz</inf> and layer thickness: a and linear dielectric layer with isotropic permittivity: ε<inf>a</inf> and layer thickness: b. This proposed formula was very simple and accurate for calculating conversion efficiency of second-harmonic generation at various incident angles of fundamental-harmonic wave and thicknesses of nonlinear hyperbolic metamaterial layer. The numerical results showed that the maximum conversion efficiency can be achieved by the strong local field confinement of fundamental-harmonic wave in the photonic hypercrystal and phase-matching due to optimal values of hypercrystal layer thickness and incident angle of fundamental-harmonic wave.
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Hybrid nanowire-hyperbolic metamaterial based broadband absorber for the visible and near-infrared regions
(2021-12-01)
Buranasiri, Prathan
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Plaipichit, Suwan
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Puttharugsa, Chokchai
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Wicharn, Surawut
In this work, spectral absorbance of hybrid nanowire-hyperbolic metamaterial was investigated numerically by using transfer-matrix method. The hybrid nanowire-hyperbolic metamaterial is consisted of two-dimensional periodically arranged arrays of subwavelength-sized hybrid nanowires (with circular cross-section) embedded in silicon dioxide host matrix. Each hybrid nanowire is made by core-shell structure used silicon as a core and gold as a shell. The hybrid nanowire-hyperbolic metamaterial is used as a top layer of a broadband absorber. The top layer is over on a planar silicon dioxide layer, which is backed by a nano-sized layer of gold as a perfect reflector for guaranteeing high absorbance. When electromagnetic waves in the range of 400–1600 nm wavelength are obliquely incident on the top hybrid nanowire-hyperbolic metamaterial surface, the absorption spectra of the designed absorber structure are analyzed for different incident angles, and radii of hybrid nanowire components or fill-factor of the hyperbolic metamaterial layer. The multiple absorption peaks, which are continuously generated from multiple longitudinal and transverse surface plasmon modes and are supported by the hybrid nanowires, are observed directly. The absorption feature can be also tuned by various operational conditions. The proposed structure is made by in-complex nano-fabricating techniques comparing with the another and it provides acceptable broadband absorptivity.
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A multi-channel optical fibre-based smartphone spectrophotometer for measuring the spectra of LED colours
(2021-07-01)
Puttharugsa, Chokchai
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Srikhirin, Toemsak
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Pipatpanukul, Chinnawut
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Houngkamhang, Nongluck
This paper demonstrates the use of a smartphone as a low-cost multi-channel optical fibre spectrophotometer suitable for physics laboratory classes. A custom-designed cradle and structure support were fabricated using 3D printing. The plastic optical fibres were arranged and inserted into the hole of the cradle to guide the light to the rear camera of the smartphone. Here, we describe the multi-channel optical fibre-based smartphone spectrophotometer for measuring the spectra of different LED colours.
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Demonstration of light absorption and light scattering using smartphones
(2020-01-01)
Malisorn, Khemchira
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Wicharn, Surawut
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Plaipichit, Suwan
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Pipatpanukul, Chinnawut
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Houngkamhang, Nongluck
This paper demonstrates the use of smartphones in an experiment of light absorption and light scattering. The LED display and camera of the smartphone are used as the light source and as the detector, respectively. The color wheel is used to choose the color of the light source to be shone through the sample for analysis. The detector directly measures the intensity of the light that passes through the sample to study light absorption according to the Beer-Lambert law. On the other hand, to investigate the light scattering, the detector orthogonally measures the intensity of the scattered light from the sample. The results of the light absorption correspond to the Beer-Lambert law. The scattered light from the sample is be measured by a smartphone. The experiment is easy to set up, without the need for any further expensive apparatus. We expect that this experiment will be useful for physics teachers to demonstrate light absorption and light scattering in the classroom or in a physics laboratory.
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A numerical investigation of broadband absorption of TE-polarized wave in photonic hypercrystal
(2020-01-01)
Reangchan, Nareephorn
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Plaipichit, Suwan
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Puttharugsa, Chokchai
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Buranasiri, Prathan
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Wicharn, Surawut
In this study, we numerically investigated the absorption properties in one-dimensional photonic hypercrystal (PHC), which was consisted of a periodically alternating layers of hyperbolic metamaterial and dielectric material. The first layer of the unit cell of the PHC is a hyperbolic metamaterial (HMM), which made of the two-dimensional square lattice arrangement of gold (Au) nanowire embedded in indium tin oxide (ITO) host and the second layer is the same dielectric material used in metamaterial system. First, the nanowire array hyperbolic metamaterial was designed for providing high extinction coefficient in visible light to near infrared region by optimizing the radius of each Au nanowires. Then, a transfer-matrix method (TMM) was used as the numerical tool for calculating the absorption spectrum of the PHC for both TE- and TM-polarization. The numerical results showed that the PHC structure provides the widest absorption spectrum in the range of 500 to 1,000 nm for TE-polarized wave incidence. The bandwidth of interesting absorption spectrum is increased when increasing the layer thickness of the composed dielectric material. The level of absorbance of PHC is enhanced by increasing the number of periods. Conversely, the absorbance of PHC structure is decreased with the greater incident angle. Finally, the fill factor of nanowire hyperbolic metamaterial will make the shifting of absorption spectrum into long-wavelength region when it is decreased. Meanwhile, the absorption of TM-polarized wave in PHC structure is too low when comparing with TE-wave case. Due to the influence of the above parameters on the absorption spectrum for TE-polarized wave, so the PHC may be used as the TE broadband absorber for energy harvesting application.
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Gold nanorod-optical fiber for sensing biomolecular interaction
(2020-01-01)
Chueaiarrom, Channarong
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Loedsapchinda, Naruenard
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Puttharugsa, Chokchai
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Pipatpanukul, Chinnawut
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Srikhirin, Toemsak
The optical fiber deposits with gold nanorods was successfully accomplished as a biosensor device which sensing to the refractive index change on the surrounding surface. The principle is based on the localized surface plasmon resonance (LSPR) occurs on the metal surface of gold nanorods (AuNRs). The gold nanorods were coated on the glass core fiber surface through the covalent bond. The uncladded area fiber optic was incubated in 5% of (3-Mercaptopropyl) trimethoxysilane (MPTMS) in ethanol for overnight to alter the thiol group on the surface. The gold nanorods with aspect ratio ⁓2.035 was deposited on thiol surface by incubation the optical fiber in gold nanorod solution for 6 hr. The sensor provides the sensitivity of 4.94×104 a.u./RIU. Moreover, antibody for blood grouping was immobilized on the AuNRs-optical fiber to detect the red blood cells. The AuNRs-optical fiber can detect A antigen on the immobilized anti-A surface with Δ%T of 0.98 and can detect B-antigen on the immobilized anti-B surface with Δ%T of 1.78. This work possesses possibility of a simple AuNRs-optical fiber to detect the biomolecular interaction. The authors would like to thank Thailand Center of Excellence in Physics for financial support.

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