High Absorption Peak Research Articles

CSA-doped PANI semiconductor nanofilms: synthesis and characterization

Camphorsulfonic acid doped polyaniline (PANI-CSA) prepared by chemical oxidative polymerization is dip coated on glass plates with three different PANI:CSA weight ratios (1:0.5, 1:1 and 1:2). Films of thickness being <100 nm are termed as nanofilms. Fourier transform infrared spectroscopy indicated the presence of dopant and increase in degree of polymerization with increase in dopant level. X-ray diffraction studies revealed the amorphous nature of the films. Scanning electron microscopy showed very smooth morphology without any crack or pores. Hall-effect analysis showed that the increase in CSA weight ratio appreciably increases the conductivity of PANI-CSA films due to increase in carrier concentration and it also represents the semiconductivity (P-type) nature in all the films. UV–visible absorption spectra and photoluminescence spectra revealed that high intense absorption and emission peaks occur for the PANI-CSA film with PANI:CSA weight ratio (1:2). This appreciable increase is due to increase in charge carriers. Photoluminescence study of PANI-CSA films excited using 300 nm shows high intense peaks at 361 and 494 nm and a weak peak at 410 nm which confirmed the semiconducting nature of the film.

Study on split-ring-resonator based terahertz sensor and its application to the identification of product oil

Based on the finite-integration-technology method, we calculate the high and low frequency resonant peaks of the split-ring-resonators (SRRs) which served as a terahertz sensor. An equivalent three-SRRs model is introduced to understand the SRR structure at the high frequency resonant absorption peak. At the same time, an equivalent circuit is set up to calculate the high frequency resonant peak. After that, we theoretically study the sensitivity of these two peaks. The results suggest that both of these two resonant peaks show redshift when the permittivity of surrounding medium increase, and the high frequency peak is more sensitive to this permittivity variation than the low one. The SRR sample is fabricated using a surface micromachining process and used to identify gasoline of 93# and 97#. The experiment results show that the redshift of the high frequency resonant peak is larger than that of the low one, and it is in good agreement with theory analysis. This study suggests that the SRR is a good sensor to identify the product oil, and its high frequency resonant peak is more sensitive to the variation of the permittivity than the low one.

Record efficient upconverter solar cell devices with optimized bifacial silicon solar cells and monocrystalline BaY2F8:30% Er3+ upconverter

In this paper, we investigate Er3+-doped monocrystalline BaY2F8 as an upconverter material for crystalline silicon solar cells with the aim of making use of previously not-utilized sub-bandgap photons. Monocrystalline samples with 10%, 20% and 30% Er3+ doping were grown in a Czochralski furnace and subsequently attached to an adapted planar bifacial silicon solar cell with a 33.4mA/cm2 short-circuit current density under one-sun AM1.5G standard measurement conditions. Optical characterization revealed that for the investigated illumination conditions the 30% Er3+-doped samples showed the most promising properties, with a very high peak absorption coefficient of 45.1cm−1 at 1493nm and a high external (internal) upconversion quantum yield of 9.5±0.7% (10.1±1.6%) under 4740±250Wm−2 monochromatic irradiation at 1520nm. Solar simulator measurements of the upconverter solar cell device using the BaY2F8:30% Er3+ sample showed an additional short-circuit current density due to upconversion ΔjSC,UC of 17.2±3.0mA/cm2 at an illumination with a solar concentration of 94±17suns, equivalent to a record relative enhancement of the short-circuit current of 0.55±0.14%. This value constitutes to our knowledge more than a doubling compared to the previously highest published values and more than a 35-fold increase compared to values published three years ago.

J2220202 超微細塑性加工と自己組織化を用いた光機能表面の開発

A new fabrication method of minute metal structures, which have optical properties of surface, on a quartz glass sustrate is reported in this paper. Minute metal structures are useful to develop metamaterials, which have artificial optical properties that have not existed in nature. The proposed fabrication method is a combination of Nano Plastic Forming (NPF) and self-organization technique by annealing. Firstly, gold thin film is deposited on a quartz glass substrate by DC spatter coater. Secondly, rectangle groove pattern is fabricated by NPF. Then, the substrate is annealed in an electric furnace to induce self-organization of he gold. Finally, SiO_2 spacer layer and gold thin film are deposited on this structure. In addition, optical extinction spectra are measured in the wavelength of visible light and near-infrared region. This structure shows high absorption peak at the wavelength of 966 nm. This absorption mechanism is discussed from the view point of electric circuit.

Synthesis of Novel Monomer with Quinoxaline Derivatives

Novel rigid dendrimer containing cross-conjugated units are synthesized from the coupling of 2-thiophene-based dendron with 5,8-dibromo-2,3-dithienylquinoxaline. The new monomer 2,3,5,8-tetrathienylquinoxaline has been successfully synthesized with moderate yield over five steps. The structure of the monomer was determined by H-NMR and C-NMR technologies. And the optical characterization of the monomer was also determined by the UV-vis and fluorescence spectrometer. The monomer has a high absorption peak at 206 nm and high emission peak at 430 nm. The monomer was freely soluble in variety of organic solvent, such as chloroform and acetonitrile.

Chromium substitution in mullite type bismuth aluminate: Bi2CrxAl4−xO9 with 0≤x≤2.0

Nominal compositions Bi2CrxAl4−xO9 with 0.0≤x≤2.0 (Δx=0.2) were prepared using appropriate amounts of nitrates dissolved in glycerine and heated at 800°C for 24h as we previously used for the preparation of solid solution series Bi2Mx/M′4−xO9 (M/M′=Fe/Al, Ga/Al and Fe/Ga). The samples were characterized using XRD, FTIR and optical microscopic techniques. Analyses of XRD data show mullite type single phase can be prepared up to x=1.2. The lattice parameters (a, b and c) increases with increasing Cr content. Further increase in x (i.e., x≥1.4) show the presence of some additional phases indicating a limiting value for Cr doping is in the range of 1.2≤x<1.4. The effect of Cr incorporation could also be observed in the infrared absorption spectra via systematic hard mode shifts of certain lattice modes, e.g. the Bi–O related vibration changes from 96cm−1 to 93cm−1 with increasing x up to 1.2 and certain intensity changes together with shift in peak positions. Interestingly, the absence of any splitting and shift of the high energy IR absorption peak at 821cm−1 as assigned to the characteristic tetrahedral type dimer, Al2O7, indicate that the Cr thus partially substitutes only the octahedrally coordinated Al. This is confirmed by Rietveld structure refinements, too.

Extraordinary optical properties in the subwavelength metallodielectric free-standing grating.

In this paper, we present a free-standing metallodielectric grating structure that can achieve multiple transmission dips and peaks at normal incidence over the visible spectrum. The amount of dips and peaks can be adjusted by the thickness of dielectric film. In our proposed structure, there are three types of resonance modes supported: Surface plasmon polarition (SPP) at horizontal metal/dielectric interface, vertical cavity mode in the metal slits, and guide mode in the dielectric film. Physically the coupling and resonant interactions among these modes lead to the generation of dips and peaks in the transmission spectrum. The transmission peaks is further interpreted by using Fano resonance. More surprisingly, the simultaneous excitation of three types of resonance modes can enhance the field distribution, which results in unexpected nearly perfect absorption in such simple structure. Moreover, compared to other absorption peaks, this high absorption peak originates from that guide mode resonance in the dielectric film inhibits transmission induced by cavity mode resonance in the metal slits. These results can be used in the design of many photonics components.

SINTESIS PATI JAGUNG TERFOSFORILASI MELALUI TEKNIK GELOMBANG MIKRO

SINTESIS PATI JAGUNG TERFOSFORILASI MELALUI TEKNIK GELOMBANG MIKRO [Microwave-Assisted Synthesis of Phosphorylated Corn Starch ] Atep Dian Supardan*, Suminar Setiati Achmadi dan Tun Tedja Irawadi Departemen Kimia, Fakultas Matematika dan Ilmu Pengetahuan Alam, Institut Pertanian Bogor, Bogor Diterima 28 Maret 2013 / Disetujui 24 Februari 2014 ABSTRACT Phosphorylated starch is a type of modified starches which is most ly imported. Commonly, starch to be modified must contain more than 25% of amylose. This study aimed to synthesize phosphorylated starch and evaluate its potency as a heavy metal adsorbent. Corn starch was subjected to phosphorylation through microwave-assisted reaction with a mixture of sodium dihydrogen orthophosphate and disodium hydrogen phosphate. The experiment was designed to optimize the pH, microwave radiation power, and phosphorylation time. The results showed that the maximum phosphate subtitution degree was obtained at pH of 6, microwave radiation of 500 W, and a reaction time of 10 minutes. The degree of subtitution ranged from 0.567 to 0.787. The physicochemical properties of the product i.e. swelling capacity, solubility, water binding capacity, and paste clarity were significantl y different than that of the unmodified corn starch. The infrared spectrum showed a high peak absorption at the wavelength of 1651 cm -1 , indicating hydrogen bond formation of phosphoric group-water- phosphoric group. In the fingerprint area, there were two new absorption peaks at 12 00 and 99 0 cm -1 , which were assigned for the P = O and C-O-P vibrations, respectively. The phosphorylated corn starch adsorbed methylene blue up to 73.3% and mercury up to 73.6%, suggesting the prospect of the microwave - assisted synthetic phosphorylated corn starch as an effective adsorbent for heavy metals.

Effect of Dye on the Performance of Nitrogen Doped TiO2 Solar Cell Prepared via Ammonia Treated Liquid Phase Deposition Technique

This paper reports the utilization of nitrogen-doped TiO2 nanoparticle in dye-sensitized solar cell (DSSC). The TiO2 nanoparticles were synthesized on ITO substrate via a simple technique, namely, liquid phase deposition (LPD). 7.5% nitrogen from NH3 dopant source was doped into the TiO2 samples by spin coating technique. The nitrogen doped TiO2 samples were then utilized as photovoltaic materials in a photoelectrochemical cell of ITO/TiO2/electrolyte/platinum sensitized with N-719, N-3 and Z-907 dyes, respectively. It was found that the photovoltaic parameters such as short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF) and power conversion efficiency (η) are influenced by the organic dyes. The cell sensitized with N-719 dye demonstrated the highest photovoltaic parameters. These results are supported with the UV-Vis analysis, showing that the N-719 dye possessed the broadest window absorption and the highest absorption peak in visible region of light spectrum.

The Effect of Variation Concentration Nd&lt;sup&gt;3+&lt;/sup&gt; Ions on Physical and Optical Properties of TZBN Glass

This study aims to determine the optical and physical properties of TZBN:Nd glass with the composition (mol%) 60TeO2-2Bi2O3-(34-x)ZnO-4Na2O-xNd2O3 with variation of doping x = 0.5; 1.0; 1.5; 2.0. Fabrication has been done by using the melt-quenching technique. Characterization of tellurite glass covering density, refractive index and absorption spectrum of glass. Density of glass have been measured using the Archimedes method. Refractive index of glass have been measured using the Brewster angle at wavelength 746.191 nm. Absorption spectrum measurements using UV-Vis-NIR spectrophotometer Perkin Elmer Lambda 25 in the region of 200-1100 nm. The results of characterization show that density / physical characteristics of glass did not increase when the concentration of ions Nd3+ to TZBN:Nd glass increased. The refractive index of glass will increase as the concentration of ions Nd3+ to TZBN:Nd glass increased. Based on the results of UV-Vis-NIR spectroscopy measurements shows that there are nine significant spectra have been observed in the region of 200-1100 nm, such as at a wavelength of 431 nm, 474 nm, 515 nm, 527 nm, 585 nm, 684 nm, 749 nm, 805 nm, and 878 nm and the highest absorption peak is at a wavelength of 585 nm.

Air Flow Resistance and Sound Absorption Behavior of Open-celled Aluminum Foams with Spherical Cells

Aluminum foams with spherical cells were produced by a pressure infiltration process, and their sound absorption behaviors were examined and correlated with the air flow resistance. It is shown that the small apertures or pore openings on the cell walls play an important role in determining the sound absorption behavior of the foams due to the significant influence on the air flow resistance of the foams. The foams with the same porosity and pore opening size but different pore sizes have similar air flow resistance and sound absorbing performance, suggesting that there is no necessary relationship between the pore size and sound absorption performance of the present aluminum foams. With decreasing the pore opening size, the air flow resistance increased and the low-frequency absorption peak shifted towards lower frequencies but the height decreased. When the two samples with different pore sizes were put together, the sound absorption behavior of the combined samples was dependent on the pore size of sample facing the sound waves. Relatively large pores in the face side lead to relatively high low-frequency absorption peak.

Novel triple-band polarization-insensitive wide-angle ultra-thin microwave metamaterial absorber

We report the design, analysis, fabrication, and measurement of a novel microwave triple-band metamaterial absorber that obtains three distinct high absorption peaks. The absorber is constructed of a periodic array of new resonant structure printed on a dielectric material with the thickness of λ/67 at the lowest fundamental resonant frequency. By manipulating the periodic patterned structures, significantly high absorption can be obtained at three specific resonance frequencies. This kind of triple-band absorber is polarization insensitive, and the absorption peaks remain high with large angles of incidence for both transverse electric and transverse magnetic polarizations, which provide more efficient absorptions for non-polarized or oblique incident electromagnetic wave. The experimental results show excellent absorption rates and the characteristic of polarization-insensitive for a wide range of incidence angles in the desired frequencies, which are in good correspondence with the simulated results.

Sonication Parameters Analysis of MWCNTs Monodispersion in Aqueous Solution of Triton X-100

Monodispersion of multi-walled carbon nanotubes with assistance of surfactants has become a usual procedure. A parametric analysis of sonication was performed in order to optimize the preparation procedure of MWCNTs monodispersion solution. MWCNTs solutions were characterized with results of UV-VIS absorbance and FT-IR spectra in order to find the optimal sonication time and power. Perfect sonication time obtained at the higher absorption peak 2.699 in 400nm is 42min, which can be define as sonication cycle. MWCNTs can achieve its optimum dispersion situation, when onication power is 270w, In this case, zeta potential can get as high as-45.2mv. Film achieved under combination of two kinds of optimization parameters is more smoothy and integrated.

Spectral radiative property control method based on filling solution

Controlling thermal radiation by tailoring spectral properties of microstructure is a promising method, can be applied in many industrial systems and have been widely researched recently. Among various property tailoring schemes, geometry design of microstructures is a commonly used method. However, the existing radiation property tailoring is limited by adjustability of processed microstructures. In other words, the spectral radiative properties of microscale structures are not possible to change after the gratings are fabricated. In this paper, we propose a method that adjusts the grating spectral properties by means of injecting filling solution, which could modify the thermal radiation in a fabricated microstructure. Therefore, this method overcomes the limitation mentioned above. Both mercury and water are adopted as the filling solution in this study. Aluminum and silver are selected as the grating materials to investigate the generality and limitation of this control method. The rigorous coupled-wave analysis is used to investigate the spectral radiative properties of these filling solution grating structures. A magnetic polaritons mechanism identification method is proposed based on LC circuit model principle. It is found that this control method could be used by different grating materials. Different filling solutions would enable the high absorption peak to move to longer or shorter wavelength band. The results show that the filling solution grating structures are promising for active control of spectral radiative properties.

Widening Absorption Band of Grating Structure With Complex Dual-Groove Grating

The wavelength-selective radiative property is becoming a noticeable requirement in various technological fields. There are many researches that have been focused on the radiative properties of metal periodic microstructure surface. However, the spectral bandwidth of high absorptance is often too narrow if excited by the conventional grating structures. In order to solve this problem, two novel periodic grating structures are proposed in this paper, which can increase the effective bandwidth of high absorption peaks. One of the new periodic grating structures, called dual-groove grating, is constructed by adding a rectangular groove at the bottom of the simple grating's groove through a secondary microscale processing. The other grating structure, which is called complex dual-groove grating, is constructed by superposing a dual-groove grating with a simple grating within one period. Aluminum grating structure is taken as an example to show the advantage of proposed structures on increasing effective bandwidth of high absorption peaks within mid-infrared and far-infrared spectra. The rigorous coupled-wave analysis (RCWA) is used to calculate the absorptance of periodic grating structures. The results shows that, two close absorption peaks and three connecting absorption peaks are obtained respectively for the two periodic grating structures. The effective bandwidth of high absorption peaks within interested wavelength band is improved obviously by these two microscale grating structures.

Specific absorption spectra of hemoglobin at different PO2 levels: potential noninvasive method to detect PO2 in tissues

Hemoglobin (Hb), as one of main components of blood, has a unique quaternary structure. Its release of oxygen is controlled by oxygen partial pressure (PO2). We investigate the specific spectroscopic changes in Hb under different PO2 levels to optimize clinical methods of measuring tissue PO2. The transmissivity of Hb under different PO2 levels is measured with a UV/Vis fiber optic spectrometer. Its plotted absorption spectral curve shows two high absorption peaks at 540 and 576 nm and an absorption valley at 560 nm when PO2 is higher than 100 mm Hg. The two high absorption peaks decrease gradually with a decrease in PO2, whereas the absorption valley at 560 nm increases. When PO2 decreases to approximately 0 mm Hg, the two high absorption peaks disappear completely, while the absorption valley has a hypochromic shift (8 to 10 nm) and forms a specific high absorption peak at approximately 550 nm. The same phenomena can be observed in visible reflectance spectra of finger-tip microcirculation. Specific changes in extinction coefficient and absorption spectra of Hb occur along with variations in PO2, which could be used to explain pathological changes caused by tissue hypoxia and for early detection of oxygen deficiency diseases in clinical monitoring.

Design of input couplers for efficient silicon thin film solar absorbers

We investigated light absorption in various Si thin film solar absorbers and designed efficient input couplers using finite-difference time-domain simulation. In the simulation, a dielectric coating on Si thin film led to enhanced light absorption at near-ultraviolet to blue wavelengths, while the absorption peaks at longer wavelengths were nearly preserved. In a 300-nm-thick Si film with a 60-nm-thick Si(3)N(4) top-coated layer, current density was augmented by ~35% compared to a bare Si film. For broadband absorption, we introduced two-dimensional square-lattice periodic patterns consisting of low-index dielectric materials, SiO(2) or Si(3)N(4), or high-index material, Si. The periodic pattern exhibited tunable and pronounced absorption peaks that are identified as horizontally-propagating waveguide modes. The high absorption peaks were significantly amplified with increasing refractive index of the dielectric pattern. For a Si-patterned structure with a pitch size of 400 nm and a pattern depth of 80 nm, current density was achieved up to 17.0 mA/cm(2), which is enhanced by a factor of 2.1 compared to the current density of bare Si film. Deep understanding of the light absorption in optical cavities with wavelength-scale thickness will be useful in the design of efficient thin film solar absorbers as well as novel nanophotonic elements.

DFT/TDDFT investigation of the electronic structures and optoelectronic properties of phosphorescent iridium (III) complexes with non-conjugated cyclometalated carbene ligands

This work investigates the electronic structures and spectroscopic properties of several cyclometalated iridium carbene complexes possessing at least one functionalized methylene moiety, (dfpmb)(dfbmb)Ir(mptz) (2), (dfbmb)2Ir(mptz) (3), and (dfbmb)2Ir(mpmtz) (4) (dfpmbH =1-difluorophenyl-3-methyl-benzimidazoline-2-ylidene; dfbmbH = 1-(2,4-difluorobenzyl)-3-(methylbenzimidazolium; mptzH = 4-methyl-2-(5-(trifluoromethyl)-2H-1,2,4-triazol-3-yl)pyridine); mpmtzH = 4-methyl-2-(3-methylene-5-(trifluoromethyl)- 2H-1,2,4-triazole-3-yl)pyridine) on the basis of their prototype (dfpmb)2Ir(mptz) (1) via DFT and TDDFT methods. A careful examination of results shows: (1) the patterns of the occupied orbitals for 1–4 are almost the same, with the HOMO being an admixture of the Ir atom and benzyl part, whereas the LUMO is predominately delocalized over the ancillary chelate mptz or mpmtz; (2) complexes 1–3, and especially 4, all exhibit blue emission with maximum wavelengths at 506, 495, 486, and 478 nm, respectively; (3) complex 4 with the highest (relative) component of 3MLCT can be reasonably expected to have a higher radiative transition rate constant (kr ) among 1–4. From the highest absorption peaks, eventually, the molar extinction coefficient discrepancy between experiment and calculations might be tentatively attributable to the synergism of the intrinsic imperfection of the PCM model and the simplification of chemical computations.

Synthesis and thermal study of octahedral silver nano-plates in polyvinyl alcohol (PVA)

Octahedral silver nano-plates were synthesized from aqueous solution of silver nitrate and polyvinyl alcohol. The colloid formed is dried on glass plates by simple dip-coating method to inhibit the growth of the particles, and to analyze the samples. Samples were characterized by X-ray diffractometer, transmission electron microscope (TEM), thermo-gravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. The UV–Vis absorption spectra of these silver nano-plates revealed a high intense plasmon absorption peak near 425nm. In addition three emission peaks were observed when the excitation was fixed at 222nm.

분광분석을 통한 지르콘의 메타믹상태와 색상 변화 분석

캄보디아와 탄자니아산 지르콘을 대상으로 메타믹상태와 색상변화에 대한 연구를 하였다. 이를 위해 U, Th 등의 방사성원소 검출을 위한 원소분석과 분광분석(UV-VIS 분광기, FTIR분광기)을 하였다. UV-VIS 분광분석 결과 청색과 무색에서는 고온형의 특징인 많은 흡수 피크들과 세기가 높게 나타났으며 우라늄이 검출된 녹색과 황색 시료에서는 흡수 피크들의 수가 현저히 적게 나타나 메타믹화가 진행되었음을 알 수 있었다. 열처리 후에는 반대의 결과가 나왔다. FTIR 분광 분석 결과 3100~3400 <TEX>$cm^{-1}$</TEX> 영역에서 <TEX>$[SiO_4]^{4-}$</TEX> 내부 진동의 3-포논 조합 모드 밴드들이 메타믹화된 녹색과 황색의 지르콘에서는 완만하며 없어진 밴드들도 있으나 열처리 후에는 다시 결정격자가 원상태로 회복되어 사라졌던 밴드들이 나타났다. 또한 지르콘에 우라늄이 함유되어 있는지를 알 수 있는 4800 <TEX>$cm^{-1}$</TEX> 근처에서 <TEX>$U^{4+}$</TEX>의 피크가 녹색과 황색 시료에서 확인 되었다. 연구 결과 분광분석 과 열처리 실험으로 지르콘에 우라늄의 함유가 메타믹상태와 칼라의 변화에 미치는 영향을 확인할 수 있었다. Metamictization and color change in zircons from Cambodia and Tanzania were investigated. Elements analysis to detect radioactivity of elements such as U and Th, and spectroscopic analysis using UV-VIS and Fourier transform infrared spectroscopy were performed. According to the UV-VIS spectroscopic analysis, it was perceived that many and high intense absorption peaks appeared in blue and colorless zircons, while less and low intense absorption peaks appeared in uranium contained green and yellow zircons. It was found that those stones have made progress to the metamictization. After heat treatment, we could detect opposite results. As the results of FTIR spectroscopy analysis, in the metamict green and yellow zircon, it is showed that 3-phonon combination mode bands of <TEX>$[SiO_4]^{4-}$</TEX> internal vibration in the region of 3100~3400 <TEX>$cm^{-1}$</TEX> are broad and some of them disappear. However, the disappeared bands are observed again due to restored crystal lattice by the heat treatment. Also, <TEX>$U^{4+}$</TEX> peaks that can detect the uranium content in zircon appears at near 4800 <TEX>$cm^{-1}$</TEX> in the green and yellow samples. From this investigation, we could observe the metamictization effect and color change in uranium-bearing zircon by heat treatment using spectroscopic analysis.