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Influence of 120 MeV S9+ ion irradiation on structural, optical and morphological properties of zirconium oxide thin films deposited by RF sputtering
摘要： The calibrated and controlled swift heavy ions (SHI) beam irradiation generates defects which can cause modifications in various properties of the materials such as structural, optical, magnetic, morphological, and chemical etc. The passage of ion through the target material causes the nuclear energy losses (Sn) and electronic energy losses (Se). The Se dominates over Sn in SHI irradiation. In the present study, ZrO2 thin films were grown on silicon and glass substrate by using RF sputtering deposition technique. For the purpose of modifications induced by swift heavy ions, these films were irradiated by a 120 MeV S9+ ion beam of 1 pnA current, with varying ion fluences from 5E12 to 1E13 ions/cm2, using the tandem accelerator at the Inter University Accelerator Center (IUAC), New Delhi, India. The X-ray diffraction (XRD) patterns confirmed the formation of monoclinic and tetragonal phases and it was observed that XRD peak intensities increased up to the fluence of 5E12 ions/cm2 followed by opposite behavior at higher fluences. Atomic force microscope (AFM) study revealed the increased surface roughness after SHI irradiation. In addition to it, the formation of electronic transition states in optical band gap region and enhancement of absorption edge was observed from UV- visible spectroscopy (UV-Vis) results due to which direct band gap energy value decreased from those of un-irradiated samples. Photoluminescence (PL) broad emission spectra were determined using the excitation wavelength at 290 nm with the prominent peak at 415 nm which can be ascribed to Zr vacancies due to band edge emission as a result of free- exciton recombination. Rutherford backscattering spectrometry (RBS) technique was used for depth profiling and elemental composition in zirconia thin films. The expected role of electronic energy loss during ion irradiation to modify the properties of the material has been discussed.
关键词： PL,ZrO2 thin films,XRD,UV-Vis,AFM,RBS,SHI irradiation
更新于2025-09-09 09:28:46
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How To Correctly Determine the Band Gap Energy of Modified Semiconductor Photocatalysts Based on UV–Vis Spectra
摘要： A misuse of the Tauc plot to determine the band gap energy of semiconductors may lead to erroneous estimates. Particularly large errors can be associated with characterization of modified semiconductors showing a significant absorption of sub-band gap energy photons. Taking the model methyl orange/titanium dioxide system, we address the problem and discuss how to apply the Tauc method correctly.
关键词： band gap energy,UV?Vis spectra,Tauc plot,methyl orange,modified semiconductors,titanium dioxide
更新于2025-09-09 09:28:46
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Investigation on Physical Properties of Semiorganic Nonlinear Optical Glycine Zinc Sulfate Single Crystal
摘要： Nonlinear optical single crystals of Glycine Zinc Sulfate (GZS) were grown by slow evaporation technique. Single crystal X-ray diffraction analysis revealed the crystal system and lattice parameter values. Powder X-ray diffraction analyses have been carried out and the diffraction patterns have been indexed. The optical properties of the crystals were determined using UV-Visible spectroscopy. Optical constants such as band gap, refractive index, extinction coefficient and electric susceptibility were determined from UV-Visible spectroscopy. The refractive index was determined using Brewster’s angle method. Hardness of the GZS crystal was estimated by Vicker’s hardness studies. Second Harmonic Generation (SHG) of GZS crystal was investigated by Kurtz powder technique. The dielectric constant and dielectric loss measurements were carried out for different temperatures and frequencies. The photoconductivity studies confirm that the grown crystal has negative photoconductivity nature. In order to investigate the growth mechanism and surface features, etching studies are carried out for the crystal.
关键词： NLO,single X-ray diffraction,SHG,UV-Vis-NIR spectrophotometer,dielectric loss studies,dielectric constant
更新于2025-09-09 09:28:46
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Studies on zinc oxide thin films by chemical spray pyrolysis technique
摘要： Zinc oxide (ZnO) thin films were deposited by chemical spray pyrolysis (CSP) technique using zinc acetate dihydrate solutions on microscopic glass substrates by varying the precursor concentration. The prepared films were characterized structurally and optically, using the powder X-ray diffraction (XRD) and UV analysis and Photoluminescence analysis. Crystallographic properties were analyzed through powder XRD. The XRD patterns shows a hexagonal structure with c-axis orientation (0 0 2) on self texturing phenomenon. Optical transmittance properties of the optimized ZnO thin films were investigated by using UV-Vis spectroscopy. The optical studies predicated a maximum transmittance in the range of above 70% with direct band gap values in the range of 2.9 to 3.2eV for the zinc oxide thin films. Under excitation of 300 nm radiations, sharp deep level emission peak at 2.506 eV dominates the photoluminescence spectra with weak deep level and near band edge emission peak at 3.026 and 3.427 eV respectively.
关键词： Photoluminescence,Transparent conducting oxide (TCO),UV-Vis,Zinc Oxide thin film,CSP technique,X-ray diffraction (XRD)
更新于2025-09-09 09:28:46
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Lewis Acid Modulation of meso-Pyridyl BODIPY Chromophores
摘要： Two pyridyl-substituted BODIPY compounds are shown to interact with the strong Lewis acid B(C6F5)3. The borane adducts are characterized by multinuclear NMR and in one case by X-ray crystallography. The titration of pyridyl-substituted BODIPYs with B(C6F5)3 results in a bathochromic shift of the UV-vis absorption and emission spectra, with the magnitude of the shift depending on the distance of the bound borane from the BODIPY core. In meso-4-pyridyl-BODIPY, binding of B(C6F5)3 induces a small ca. 230 cm?1 red shift in the UV-vis absorption maximum, with a much larger 1950 cm?1 shift in the photoluminescence maximum. In meso-4-pyridylphenyl-BODIPY, where the pyridine Lewis base is separated from the BODIPY core by a phenyl spacer, smaller shifts of ca. 120 cm?1 in UV-vis absorption and 330 cm?1 in photoluminescence are observed. This work shows that these organic chromophores can interact with Lewis acids as a means of systematically perturbing the electronic structure and excited-state properties.
关键词： Boron,UV/Vis Spectroscopy,Lewis acids,Fluorescence,BODIPY
更新于2025-09-09 09:28:46
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Understanding perceived color through gradual spectroscopic variations in electrochromism
摘要： A bias-dependent in situ Raman scattering and UV–Vis absorption spectroscopic change has been correlated with the corresponding color change of an electrochromic device in an attempt to explain how to understand the relationship between actual perceived color and its absorption/transmittance spectra. For this, the bias across an electrochromic device was increased gradually, rather than abruptly turning ON and OFF, to see subtle variations in Raman and absorption spectra due to bias. Raman scattering establishes that viologen changes its oxidation state reversibly between two redox species (EV2? to EV??) as a result of bias-induced dynamic redox process. A gradual variation in Raman and absorption spectra, which shows maximum absorption corresponding to the yellow light, accompanies similar variation in color change of the device as visible by naked eye. These spectroscopic results are correlated with the perceived blue color, in the re?ected light, by the eye to understand the actual reason behind this. Maximum absorption of yellow light by the device resulting in blue appearance has been explained using the concept of additive and subtractive primary colors.
关键词： Viologen,Raman spectroscopy,UV–Vis,Electrochromism
更新于2025-09-09 09:28:46
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Reflectance spectroscopy of ammonium-bearing phyllosilicates
摘要： The identification of NH4-bearing phyllosilicates on Ceres poses the question on the NH4-carrier phase(s) and in this study we describe the laboratory production and IR spectroscopic measurements of a suite of ten NH4-phyllosilicates, starting from the corresponding NH4-free minerals. For each mineral, we prepared three types of powder samples: raw (R), ammoniated (A), and leached (L). All samples have been spectrally characterized by means of visible/infrared spectroscopy in the INAF-IAPS laboratories with the FieldSpec Pro in the 0.35-2.5 μm range, and with the FT-IR, using a Vertex 80 spectrometer operating in the range of 2 to 14 μm. The samples were also measured with the SPectral IMager, an imaging spectrometer operating in the spectral range 0.2 – 5.1 μm, which is a replica of the VIR spectrometer on-board Dawn spacecraft. Reflectance spectra of the ammoniated clays show bands near 1.56 μm, 2.05 μm, 2.12 μm, 3.06 μm, 3.25 μm, 3.55 μm, 4.2 μm, 5.7 μm and 7.0 μm that are related to the presence of nitrogen complexes. Treatment of phyllosilicates with ammonia shows that different minerals behave in different ways: NH4+ ions are easily accepted by the smectites, while other non-expandable structures do not accept these ions. The obtained results can be used to better constrain the NH4-bearing species present on Ceres and, possibly, other bodies of the solar system.
关键词： Reflectance spectroscopy,smectites,VIS-NIR spectroscopy,Ceres,ammonium-bearing phyllosilicates
更新于2025-09-09 09:28:46
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A novel pro-apoptotic role of zinc octacarboxyphthalocyanine in melanoma me45 cancer cell's photodynamic therapy (PDT)
摘要： Zn-based phthalocyanine acts as drug or photosensitizer in photodynamic therapy (PDT) for the treatment of cancer cells. The activated zinc octacarboxyphthalocyanine (ZnPcOC) reacts with oxygen, to generate reactive oxygen species for the damage of melanoma cancer cells, Me45. This in vitro study aimed at investigating the cytotoxic effects of different concentrations of ZnPcOC activated with a diode laser (λ=685 nm) on Me45, and normal human fibroblast cells, NHDF. To perform this study 104 cells/ml were seeded in 96-well plates and allowed to attach overnight, after which cells were treated with different concentrations of ZnPcOC (10, 20 and 30 μM). After 4 h, cells were irradiated with a constant light dose of 2.5; 4.5 and 7.5 J/cm2. Post-irradiated cells were incubated for 24 h before cell viability was measured using the MTT viability assay. Data indicated that high concentrations of ZnPcOC (30 μM) in its inactive state are not cytotoxic to the melanoma cancer cells and normal fibroblasts. Moreover, the results showed that photoactivated ZnPcOC (30 μM) was able to reduce the cell viability of melanoma and fibroblast to about 50%, respectively. At this photosensitizing concentration the efficacy the treatment light dose of 2.5; 4.5 and 7.5 J/cm2 was evaluated against Me45 cells. ZnPcOC at a concentration of 30 μM activated with a light dose of 2.5; 4.5 and 7.5 J/cm2 was the most efficient for the killing of melanoma cancer cells. Melanoma cancer cells after PDT with a photosensitizing concentration of 30 μM ZnPcOC and a treatment light dose of 2.5; 4.5 and 7.5 J/cm2 showed certain pro-apoptotic characteristics, such as direct inducer (early apoptosis) and long-term inducer, also (late apoptosis). This concludes that low concentrations of ZnPcOC, activated with the appropriate light dose, can be used to induce cell death in melanoma cells via ROS-induces apoptosis pathway, what was confirmed with cytometric ROS measurements. Our in vitro study showed that ZnPcOC mediated photodynamic therapy is an effective treatment option for melanoma Me45 cancer cells. 30 μM of ZnPcOC with the treatment light dose of 2.5 J/cm2 from a LED diode laser source, with a wavelength of 685 nm, was adequate to destroy melanoma cancer cells via ROS-induced apoptosis pathway, with low killing effects on healthy NHDF normal fibroblasts.
关键词： photosensitizers,zinc octacarboxyphthalocyanine (ZnPcOC),UV-Vis spectra,pro-apoptotic activity,photodynamic therapy (PDT),reactive oxygen species (ROS),melanoma Me45 cancer cells
更新于2025-09-09 09:28:46
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Dose response and stability of water equivalent PRESAGE <sup>?</sup> dosimeters for synchrotron radiation therapy dosimetry
摘要： This research investigated the dose response and post-irradiation stability of water-equivalent PRESAGE? dosimeters exposed to synchrotron radiation. Water-equivalent PRESAGE? dosimeters were irradiated up to 1000 Gy in a synchrotron x-ray beam with a mean energy of 95.3 keV. The change in optical density was measured using UV/visible spectrophotometry pre- and post-irradiation using a wavelength of 630 nm. Dose response was found to be approximately linear from 0–200 Gy with saturation occurring above 300 Gy. The post-irradiation stability was determined by measuring the change in optical density at 10, 30, 60, 180, 420 min and 7, 21 and 33 d post-irradiation for three groups of dosimeters stored at different temperatures. Each group had two dosimeters irradiated at 50, 100, 200 and 300 Gy and each group was stored at a different temperature following irradiation: room temperature (22 °C), 4 °C and ?18 °C. The optimal time for readout of the dosimeters varied with the post-irradiation storage temperature. The room temperature group had an optimal time-to-readout of 10 min for maximum signal before fading, while the 4 °C group was reasonably stable from 90 min to 1 week. The ?18 °C group showed the least amount of ongoing post-irradiation development and fading with an optimal readout window from 30 min to 21 d. The intra-batch variation between the mean of each temperature control group was 4.2% at 10 min post-irradiation.
关键词： PRESAGE? dosimeter,synchrotron radiation therapy,UV/Vis spectrophotometry
更新于2025-09-09 09:28:46
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SPECTROSCOPIC STUDIES ON POUZOLZIA WIGHTII BENN
摘要： Objective: The present study was aimed to reveal the spectroscopic profile (UV-Vis and FT-IR) of Pouzolzia wightii Benn. Methods: To detect the UV-Vis spectroscopic profile of P. wightii crude extracts were examined under UV-Vis Shimadzu spectrophotometer with the wavelength ranged from 100 to 1100 nm. About 1 mg of different extracts of petroleum ether, chloroform, ethyl acetate and acetone, ethanolic extracts of P. wightii were separately made into thin discs with 10-100 mg of potassium bromide using a mould and pressed under anhydrous conditions. The pellets were measured in an automatic recording FT-IR Spectrophotometer (Shimadzu 8400S) in the range of 400 to 4000 cm-1 Results: In UV-Vis analysis, P. wightii petroleum ether extracts showed more number of peaks in roots (15) than other studied parts. Chloroform and ethyl acetate extracts of P. wightii leaves observed 9 peaks and acetone extracts of P. wightii stem showed 10 peaks. Medicinal property of plant extracts are confirmed by the presence of secondary metabolites. FT-IR analysis of ethyl acetate extracts of P. wightii leaves, stem and root observed the highest number of (16, 12 and 16) functional compounds. Conclusion: These UV-Vis and FT-IR spectroscopic results may be used as a pharmacognostic marker in the pharmaceutical industries and can be used as a chemometric tool to distinguish the studied P. wightii leaves, stem and root. The present study used to find out the bioactive compounds which may be subjected to subsequent target isolation. Further research will be needed for the structural characterization of the isolated compound by the use of different analytical methods such as NMR and mass spectrophotometer.
关键词： Pharmacognosy,FT-IR-Fourier Transform-Infra Red,Pouzolzia wightii,UV-Vis-Ultra Violet–Visible
更新于2025-09-04 15:30:14