Locharoenrat, Kitsakorn

Preferred name

Alternative Name

LOCHAROENRAT, KITSAKORN

Locharoenrat, K.

Main Affiliation

School of Science

kitsakorn.lo@kmitl.ac.th

Now showing 1 - 10 of 51

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Optical properties of solids: An introductory textbook
(2016-03-23)
Locharoenrat, Kitsakorn
This textbook presents the general point of views of the optical properties of solids and gives an overview of the landscape of optics in solid-state materials, especially focusing on optical imaging techniques. It presents the background of electromagnetic theory, which is based on Maxwell's equations. It shows how to manipulate Maxwell's equations in differential forms by utilizing vector analysis and how to calculate the electric field emerging from a single charge and from charge distributions in conductors and dielectrics under Maxwell's boundary conditions. It analyzes the optical spectra from localized electronic states and goes over some well-known phenomena currently under research, such as nonlinear optical response of materials. It also gives a background on optical microscopy, focusing on the optical response of modern confocal microscopy on asymmetric materials, and introduces optical tomographic techniques to identify the locations and profiles of matter, concentrating on fluorescence diffuse optical tomography used as a probe in deep biological tissue. The book is designed for all kinds of learners, especially independent learners, and is aimed to facilitate the visualization of related theoretical concepts. Problem sets have been provided with each chapter to examine the readers' understanding of each concept.
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Rhodamine 6G and Au–Pd core–shell nanorods: Fluorescence enhancement for detection of mercury
(2018-01-01)
Rammarat, Ekkachai
;
Kraithong, Sasiwimon
;
Wanichacheva, Nantanit
;
Swanglap, Pattanawit
;
Yindeesuk, Witoon
We show that hybrid organic–inorganic particles are efficient for accurate sensing of mercury ions and following up trace amounts of the mercury pollutions spread in the environment. The process of synthesis of a working substance starts from preparation of rhodamine 6G derivative. Then the dye molecules are bound on the surface of Au–Pd core–shell nanorods. Mercury ions with different concentrations are finally attached onto this fluorescence sensor. Fluorescence emission of the sensor is detected with a luminescence spectrophotometer. The experimental results demonstrate that the fluorescence intensity of one of our sensors, a sensor B, is remarkably enhanced when the mercury-ion concentration increases from 0 to 15.5 µM. The limit of detection of the ions is as low as 20.6 nM. The working mechanism of our fluorescence sensor can be explained through the fluorescence-energy transfer and the plasmonic effect associated with spirolactam forms of rhodamine and conducting bimetallic nanoparticles.
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Enhancement of fluorescence in inorganic dyes by metallic nanostructured surfaces
(2016-01-01)
Locharoenrat, Kitsakorn
;
Damrongsak, Pattareeya
We have studied the influence of shape and chemical content of metallic nanostructures (gold-palladium core-shell nanorods, gold nanobipyramids and single-crystalline porous palladium nanocrystals) on the luminescence of Rhodamine 6G and Coumarin153 dyes. The changes found in the emission intensity are attributed to different proportions of the dyes and the metallic nanostructures. The enhancement of the fluorescence observed by us for the cases of Rhodamine 6G with gold-palladium core-shell nanorods and Rhodamine 6G with gold nanobipyramids suggests their promising plasmonic properties. This may be regarded as a preliminary step towards development of the fluorescent probes possessing high photo-sensitivity.
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Removal of metals using a ZnO/Au composite under visible-light illumination
(2018-01-01)
Thonglim, P.
;
Sirivichai, M.
;
Thanjai, O.
;
Locharoenrat, K.
Gold nanoparticles embedded into a ZnO film are prepared with a simple spin-coating technique. Photocatalytic performance of the film is studied under irradiation with the visible light. We suggest to increase the amount of Au nanoparticles in the ZnO matrix (from 0 to 400 mg in our particular case) to improve photocatalytic efficiency of the film via a combination of plasmonic-resonance and Schottky-barrier effects. We choose Fe2+ as a model representative of metals available in the wastewater. It is demonstrated that the ZnO/Au films with increased Au content reduce efficiently the amount of ferrum ions in the water solution. In particular, the film with the content ratio ZnO:Au = 1:2 serves as a good absorber for removing Fe2+ in case if their initial concentration is equal to 0.2 mM.
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Optical studies of zinc oxide nanoparticles and their biomedical application
(2015-01-01)
Locharoenrat, Kitsakorn
;
Srivatcharakul, Suttijit
Zinc oxide nanoparticles are prepared using the pulsed laser ablation approach (Nd:YAG laser at a central wavelength of 1064 nm with the pulse energy of 100 milli-joules) of the zinc metal plate immersed in a solution of sodium dodecyl sulfate at the ambient temperature. The laser fluence dependence of absorbance of the produced nanoparticles shows a single and sharp peak around 375 nm, indicating that the nanoparticles have a narrow size (45 - 60 nm) with almost spherical shape. Next, zinc oxide nanoparticles with different concentrations can hold promise in the phototoxic effect. The photocatalysis activity of the zinc oxide nanoparticles can considerably enhance the injury of a cancer cell mediated by the reactive oxygen species.
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Structure and piezoelectric properties of aluminum nitride thin films on quartz substrates deposited by reactive RF-magnetron sputtering
(2013-07-08)
Thedsakhulwong, Amorn
;
Locharoenrat, Kitsakorn
;
Thowladda, Warawoot
This paper presents the effect of nitrogen concentration (C<inf>N</inf>) on aluminum-nitride bonding formation, structure and morphology of the aluminum nitride films. The films on the unheated substrates were deposited by radio frequency reactive magnetron sputtering technology using an aluminum target under argon/nitrogen mixture atmosphere. The FTIR and Raman spectra of the films confirmed their absorption bands corresponding to E<inf>1</inf> (TO), A<inf>1</inf> (TO), and E<inf>2</inf> (high) vibration modes of the infrared active aluminum-nitride bonding. The crystallographic orientation of the films was optimized under C<inf>N</inf> of 40%. The cross-sectional FE-SEM image of the film under this condition showed the columnar structure. The dense columnar grains were uniformly observed on the films surface under all C<inf>N</inf>, except for C<inf>N</inf> of 20%. The bulk resistivity and piezoelectric property were investigated via the metal-insulator-metal structures. The results showed that the resistivity was in a range of 1014-1015 Ωcm while the effective piezoelectric coefficient was 11.03 pm/V. © (2013) Trans Tech Publications, Switzerland.
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Copper nanowires on NaCl (110) template
(2013-04-29)
Locharoenrat, Kitsakorn
We studied optical properties of copper nanowires fabricated by a shadow deposition method. We found that the optical absorption spectra of thinner nanowires exhibited stronger anisotropic absorption than thickner nanowires. Absorption maxima are located at lower photon energy when incident field is parallel to the wire axes than they are perpendicular to each other. They also shift to lower energy when the widths of nanowires are increased. © (2013) Trans Tech Publications, Switzerland.
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Second harmonic generation based on strong field enhancement in metallic nanostructured surface
(2014-01-01)
Locharoenrat, Kitsakorn
Although absorption is still the primary optical property of interest, other spectroscopic techniques including optical second harmonic generation (SHG) are also used to understand anisotropic nature of nanomaterials. Benefit of SHG technique as compared with linear optical approach is that SH response is the most sensitive to surface potential changes and SH intensity mainly comes from surface/interface layers. This article reports that optical absorption spectra due to surface plasmon modes of metallic nanowires exhibit strong anisotropic absorption. Maxwell-Garnett simulation cannot fit with experimental results because of wire sizes much larger than wavelength of light, whereas finite-difference timedomain calculation can fit well with experimental findings in terms of position of photon energy of absorption peak with respect to polarization conditions.
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Nitrogen concentrations on structural and optical properties of aluminum nitride films deposited by reactive RF-magnetron sputtering
(2013-02-04)
Thedsakhulwong, Amorn
;
Locharoenrat, Kitsakorn
;
Thowladda, Warawoot
We have fabricated Aluminum Nitride (AlN) films on the quartz substrates using RFreactive magnetron sputtering method. The conditions of the films have been performed under different concentration ratios between nitrogen and argon. We have found that all obtained films were transparent in visible wavelength. By using X-ray diffraction (XRD) technique, it was found that the (002), (102) and (103) orientations were shown in XRD patterns. The (002) orientation was dominant when nitrogen concentration (C<inf>N</inf>) was at 40%. On the other hand, the refractive index and optical band gap energy of the films were determined as a function of C<inf>N</inf>. We have found that the refractive index weakly depended on C<inf>N</inf>, while optical band gap energy did not. © (2013) Trans Tech Publications, Switzerland.
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Calculation of Lead-Iron Double-Layer Thickness for Gamma-Ray Shielding by MATLAB Program
(2017-01-01)
Lekchaum, Sarai
;
Locharoenrat, Kitsakorn
This contribution is aimed at designing the optimal thickness of lead-iron double-layer container to store a radioactive waste releasing the photon energy at 1.3325 MeV and initial radiation intensity at 100 mSv/hr using the optimization design by MATLAB software. This design consisted of three parts of calculations to achieve 1000 times the radiation attenuation of container. The first was the logarithmic interpolation for the mass attenuation coefficient. The second was the bilogarithmic interpolation for the exposure buildup factor. The third was the contour-plotting analytical technique for the optimal thickness of radiation container. The values of mass attenuation coefficient and exposure buildup factor were exactly validated as compared with the standard reference database. Furthermore, we have found that the optimal thickness was 3.2 cm for lead (1st layer) and 17.0 cm for iron (2nd layer). Container weight was 994.30 kg, whilst container cost was 167.30 USD. The benefit of our design can quickly and precisely apply for the radiation safety assessment of the occupational radiation workers who always work in the nuclear reactor area.

Locharoenrat, Kitsakorn

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