KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/kmitl/1

Browse

Search Results

Now showing 1 - 9 of 9

Some of the metrics are blocked by your
consent settings
Hydrothermally grown ZnO nanorods on cellulose filter papers for piezo-photocatalysis applications
(2025-12-01)
Songpanit, Maneerat
;
Limwichean, Saksorn
;
Horprathum, Mati
;
Boonyarattanakalin, Kanokthip
;
Pecharapa, Wisanu
ZnO nanorods were grown on cellulose filter paper using a one-pot hydrothermal method, varying concentrations at 10, 50, and 100 mM. The growth of ZnO nanorods exhibited high crystallinity in ZnO wurtzite confirmed by XRD and SEM results. Meanwhile, the specific surface area of all samples decreased following higher seed concentrations. To evaluate the photocatalytic performance, all samples were tested using RhB degradation under xenon irradiation, ultrasonic treatment, and a combination of xenon and ultrasonic irradiation. The highest ZnO catalytic performance in photocatalytic and piezo-catalytic reactions was observed at a 50 mM seed layer concentration attributing to the strong crystallinity along the c-axis direction and high aspect ratio of nanorods. Moreover, the optimal condition for piezo-photocatalytic applications was achieved by the seed layer concentration at 10 mM, resulting in shorter nanorods and a large surface area, providing better mechanical stability under stress corresponding to enhancing the charge recombination in photocatalytic processes.
1
Some of the metrics are blocked by your
consent settings
Fabrication of Al/Au hybrid SERS substrate using laser engraving for rapid detection of melamine and its analogues by hand-held Raman spectrometer
(2024-05-01)
Wongwasuratthakul, Puwasit
;
Aumpalop, Weerada
;
Chakaja, Chaiwat
;
Satapornchai, Pemika
;
Eiamsamut, Ploypailin
Surface-enhanced Raman spectroscopy (SERS), combined with a handheld Raman spectrometer, was utilized for the rapid and highly sensitive detection of melamine and its analogues. The investigation focused on the hybrid micro-nano structures of SERS-active substrates, fabricated by laser engraving aluminum (Al) sheets and depositing gold (Au) nanoparticles using magnetron sputtering. The laser engraving frequency was varied to get optimum SERS substrate. The fabricated SERS substrates were tested with rhodamine 6G (R6G) to optimize the Raman signal and subsequently detect melamine and its analogues viz., cyanuric acid, ammeline, ammelide in milk samples. The results demonstrated that a laser frequency of 20 kHz was the optimal condition for fabricating a micro-nano Al template with a depth of 61.21 μm, providing the highest Raman signal for R6G. The limit of detection (LOD) for melamine in mild acid solution and milk samples were determined to be 1x10-5 M and 1x10-4 M, respectively. The laser-engraved Al sheet technique offers a cost-effective approach for SERS substrate fabrication. The integration of the Al/Au hybrid SERS substrate with a hand-held Raman spectrometer demonstrates significant potential for detecting melamine and its analogues in realistic environments.
3
Some of the metrics are blocked by your
consent settings
Evaluating Noise Reduction Methods for Raman Spectroscopy in Transmission and Reflection Configurations
(2024-05-01)
Sassuvun, Wasunun
;
Buranasiri, Prathan
;
Wicharn, Surawut
;
Puttharugsa, Chokchai
;
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.
Some of the metrics are blocked by your
consent settings
Tailoring the structural and optical properties of fabricated TiO2 thin films by O2 duty cycle in reactive gas-timing magnetron sputtering
(2023-08-01)
Chittinan, Donyawan
;
Buranasiri, Prathan
;
Lertvanithphol, Tossaporn
;
Eiamchai, Pitak
;
Tantiwanichapan, Khwanchai
Titanium dioxide (TiO<inf>2</inf>) thin films were deposited on silicon (100) and glass substrates via conventional reactive sputtering and reactive gas-timing (RGT) sputtering techniques. The duty cycle of supplied O<inf>2</inf> gas determined its effect on the properties of the TiO<inf>2</inf> films through spectroscopic ellipsometry (SE). With the best triple-layer model for SE fitting, the films' structure and optical properties were analyzed and compared. The high-resolution transmission electron microscope (HR-TEM) showed good agreement with the structure of the SE model, while the grazing-incidence X-ray diffraction (GIXRD) confirmed the crystallinity of the films. The results showed that the duty cycle was a crucial factor in the deposition rate and crystalline phase of the TiO<inf>2</inf> films. The optical reflectance (%R) spectra were measured by a UV-VIS-NIR spectrophotometer, representing anti-reflection properties at a specific wavelength related to the duty cycle. Moreover, the omnidirectional optical transmittance (Omni-T) profiles were also determined. The results showed that the transmittances (%T) of TiO<inf>2</inf> film near those specific wavelengths were enhanced over the bare glass substrate at a wide angle. In addition, photoelectron spectroscopy (PES) was used to confirm the chemical states and atomic compositions.
Some of the metrics are blocked by your
consent settings
Structural and Optical Characterizations of Polymethyl Methacrylate Films with the Incorporation of Ultrafine SiO2/TiO2 Composites Utilized as Self-Cleaning Surfaces
(2023-08-01)
Songpanit, Maneerat
;
Boonyarattanakalin, Kanokthip
;
Limwichean, Saksorn
;
Lertvanithphol, Tossaporn
;
Horprathum, Mati
The structural and optical characterizations of nanocomposite films of polymethyl methacrylate (PMMA) and SiO<inf>2</inf>/TiO<inf>2</inf> composites prepared via the spin-coating technique were investigated using different SiO<inf>2</inf>:TiO<inf>2</inf> ratios. The SiO<inf>2</inf>/TiO<inf>2</inf> nanocomposites were synthesized using the sonochemical process with Si:Ti precursor ratios of 1:0.1, 1:0.5, 1:1, 1:2, 1:4, and 0:1. All characterizations of ultrafine SiO<inf>2</inf>/TiO<inf>2</inf> particles were loaded at 1 wt.% in a PMMA matrix for the fabrication of transparent SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films. The phase structure and morphology of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films were monitored using X-ray diffraction, optical microscopy, and field-emission scanning electron microscopy. A surface roughness analysis of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA nanocomposite films was conducted using atomic force microscopy. For optical characterization, transmission properties with different incident angles of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films were analyzed with UV-vis spectrophotometry. The water contact angles of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA composite films were analyzed to identify hydrophilic properties on film surfaces. Photocatalytic reactions in SiO<inf>2</inf>TiO<inf>2</inf> composite films under UV irradiation were evaluated using rhodamine B dye degradation. The optimal condition of SiO<inf>2</inf>/TiO<inf>2</inf>/PMMA nanocomposite films was obtained at a 1:1 SiO<inf>2</inf>:TiO<inf>2</inf> ratio in self-cleaning applications, resulting from good particle dispersion and the presence of the TiO<inf>2</inf> phase in the composite.
Some of the metrics are blocked by your
consent settings
Label free detection of multiple trace antibiotics with SERS substrates and independent components analysis
(2023-07-05)
Limwichean, Saksorn
;
Leung, Wipawanee
;
Sataporncha, Pemika
;
Houngkamhang, Nongluck
;
Nimittrakoolchai, On Uma
Surface enhanced Raman spectroscopy (SERS) has been widely studied and recognized as a powerful label-free technique for trace chemical analysis. However, its drawback in simultaneously identifying several molecular species has greatly limited its real-world applications. In this work, we reported a combination between SERS and independent component analysis (ICA) to detect several trace antibiotics which are commonly used in aquacultures, including malachite green, furazolidone, furaltadone hydrochloride, nitrofurantoin, and nitrofurazone. The analysis results indicate that the ICA method is highly effective in decomposing the measured SERS spectra. The target antibiotics could be precisely identified when the number of components and the sign of each independent component loading were properly optimized. With SERS substrates, the optimized ICA can identify trace molecules in a mixture at a concentration of 10−6 M achieving the correlation values to the reference molecular spectra of 71–98%. Furthermore, measurement results obtained from a real-world sample demonstration could also be recognized as an important basis to suggest this method is promising for monitoring antibiotics in a real aquatic environment.
Some of the metrics are blocked by your
consent settings
Study on detection of carbaryl pesticides by using surface-enhance raman spectroscopy
(2020-01-01)
Chakaja, Chaiwat
;
Limwichean, Saksorn
;
Nuntawong, Noppadon
;
Eiamchai, Pitak
;
Kalasung, Sukon
In this research, the Ag nanorod structure was used as surface enhanced Raman scattering (SERS) chip which provides a sensitive detection signal for trace analysis of carbaryl pesticide. Carbaryl in solid form was measured by using the standard Raman spectroscopy to investigate the spectrum. Carbaryl at various concentrations was prepared in acetonitrile and dropped on the SERS chip for measuring Raman spectrum by a portable Raman spectrometer. The measurement condition including laser power and exposure time were studied to test the performance of SERS chip for carbaryl detection. From the results, the SERS chip useful for enhancing the Raman scattering signal which was increased depending on the laser power and exposure time. Carbaryl can be detected on SERS chip couple with the portable Raman spectrometer with the limit of detection of 10-5 M.
1
Some of the metrics are blocked by your
consent settings
Rapid detection of cypermethrin by using surface-enhanced raman scattering technique
(2020-01-01)
Leung, Wipawanee
;
Limwichean, Saksorn
;
Nuntawong, Noppadon
;
Eiamchai, Pitak
;
Kalasung, Sukon
Cypermethrin is a toxic pesticide in the pyrethroid group. A Surface Enhanced Raman Scattering (SERS) based sensor has been developed to achieve simple pesticide sensing. In this work, rapid detection of cypermethrin by using the handheld Raman spectroscopy coupled with SERS substrate was demonstrated. SERS-active silver nanorods substrate was used to enhance Raman signals of test samples. The effect of exposure time and drop volume of sample was studied for cypermethrin measurement. The results found that the silver nanorods substrate can be used to measure cypermethrin in the range of 10-6 to 10-3 M with a handheld Raman spectrometer. Furthermore, the Raman signal of cypermethrin was confirmed by measuring solid cypermethrin with the standard Raman spectrometer. SERS substrate was competent to detect cypermethrin with a limit of detection (LOD) of 10-6 M.
Some of the metrics are blocked by your
consent settings
Determination of thickness and optical properties of tantalum oxide thin films by spectroscopic ellipsometry
(2014-01-01)
Chananonnawathorn, Chanunthorn
;
Khemasiri, Narathon
;
Srichaiyaperk, Thanat
;
Samransuksamer, Benjarong
;
Horprathum, Mati
Tantalum oxide (Ta<inf>2</inf>O<inf>5</inf>) thin films were prepared, at different deposition time, by a DC reactive magnetron sputtering. During the deposition, a high-quality tantalum target was sputtered under argon and oxygen ambience on to silicon (100) and glass substrates. The prepared thin films were systematically characterized for both physical and optical properties based on spectroscopic ellipsometry (SE), and consequently confirmed by several methods. With the SE physical models, we could determine the thin film thickness as well as their inhomogeneity. The films thickness results were directly confirmed by field-emission scanning electron microscopy (FE-SEM) used to observe cross-sections, and surface profiler used to measure the physical thickness of the films. With the SE optical models, we applied both the Cauchy and Tauc-Lorentz dispersions in order to obtain the optical constants, to be directly compared with those from the Swanepoel method (SM). Our result showed that from the SE analyses, the SE physical model was obtained as the multi-layer configurations. The obtained Ta<inf>2</inf>O<inf>5</inf> thin film thickness was closely related with the measured result from the FE-SEM cross-sectional micrographs and the surface profiler. For the optical characteristic, the double layer physical model was best optimized with the Tauc Lorentz dispersion model for the most accurate results. In comparison, the SM technique also demonstrated a capability to determine both the film thickness and its refractive index only from some samples. Therefore, this study proved that the SE technique successfully and accurately determine both the physical and optical properties of the Ta<inf>2</inf>O<inf>5</inf> thin films. © (2014) Trans Tech Publications, Switzerland.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results