Energy Level Difference Research Articles

Alcohol soluble cyanopyridine based conjugated donor-acceptor polymers: Synthesis, photophysical and their charge transport behavior

Two polymers (PCT1 and PCT2) bearing cyanopyridinyl (as acceptor) and phenylene or fluorenyl (as donor) tethered with N,N-dimethylaminopropyl group (as side chain) were synthesized via Heck polymerisation technique. Both the polymers exhibit an excellent solubility in methanol and insolubility in solvents like toluene and dichlorobenzene. This specific solubility of polymers helps to avoid the intermixing of successive layers during solution processing of solar cells. Further, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and photophysical studies confirm that these polymers are having high molecular weight, high thermal stability, low optical band gap and blue light emissive nature. In addition, optical transmittance spectra of polymer thin films coated on ITO substrate disclose the transparency of 90%, which is better compared to that of poly(3,4-ethylenedioxythiophene) film (80% transparency). Furthermore, hole only mobility of polymers were investigated by c-AFM method and a mobility of 1.1×10−6 and 1.3×10−6 cm2V−1S−1 were obtained for PCT1 and PCT2, respectively. Here, the obtained mobility values are better compared to other PPV polymers which are reported to be in the order of 10−7cm2V−1S−1. More importantly, ultraviolet photoelectron spectroscopy studies reveal that the polymers coated on ITO have a very high work function of 5.45–5.50eV, thereby minimizes the energy level difference between the electrode and photoactive organic material (typically 5.7 to 6.3eV). As a whole, the utilization of these polymers as interfacial layer at the interface of ITO/active layer can reduce the potential energy loss in solar cells.

Ta2O5-TiO2 Composite Charge-trapping Dielectric for the Application of the Nonvolatile Memory

The charge-trapping memory devices with a structure Pt/Al2O3/(Ta2O5)x(TiO2)1−x/Al2O3/p-Si (x = 0.9, 0.75, 0.5, 0.25) were fabricated by using rf-sputtering and atomic layer deposition techniques. A special band alignment between (Ta2O5)x(TiO2)1−x and Si substrate was designed to enhance the memory performance by controlling the composition and dielectric constant of the charge-trapping layer and reducing the difference of the potentials at the bottom of the conduction band between (Ta2O5)x(TiO2)1−x and Si substrate. The memory device with a composite charge storage layer (Ta2O5)0.5(TiO2)0.5 shows a density of trapped charges 3.84 × 1013/cm2 at ± 12 V, a programming/erasing speed of 1 µs at ± 10 V, a 8% degradation of the memory window at ± 10 V after 104 programming/erasing cycles and a 32% losing of trapped charges after ten years. The difference among the activation energies of the trapped electrons in (Ta2O5)x(TiO2)1−x CTM devices indicates that the retention characteristics are dominated by the difference of energy level for the trap sites in each TTO CTM device.

Diet density during the first week of life: Effects on energy and nitrogen balance characteristics of broiler chickens

This study aimed to determine effects of diet density on growth performance, energy balance, and nitrogen (N) balance characteristics of broiler chickens during the first wk of life. Effects of diet density were studied using a dose-response design consisting of 5 dietary fat levels (3.5, 7.0, 10.5, 14.0, and 17.5%). The relative difference in dietary energy level was used to increase amino acid levels, mineral levels, and the premix inclusion level at the same ratio. Chickens were housed in open-circuit climate respiration chambers from d 0 to 7 after hatch. Body weight was measured on d 0 and 7, whereas feed intake was determined daily. For calculation of energy balances, O2 and CO2 exchange were measured continuously and all excreta from d 0 to 7 was collected and analyzed at d 7. Average daily gain (ADG) and average daily feed intake (ADFI) decreased linearly (P = 0.047 and P < 0.001, respectively), whereas gain to feed ratio increased (P < 0.001) with increasing diet density. Gross energy (GE) intake and metabolizable energy (ME) intake were not affected by diet density, but the ratio between ME and GE intake decreased linearly with increasing diet density (P = 0.006). Fat, N, and GE efficiencies (expressed as gain per unit of nutrient intake), heat production, and respiratory exchange ratio (CO2 to O2 ratio) decreased linearly (P < 0.001) as diet density increased. Energy retention, N intake, and N retention were not affected by diet density. We conclude that a higher diet density in the first wk of life of broiler chickens did not affect protein and fat retention, whereas the ME to GE ratio decreased linearly with increased diet density. This suggests that diet density appears to affect digestibility rather than utilization of nutrients.

Modeling speech localization, talker identification, and word recognition in a multi-talker setting.

This study introduces a model for solving three different auditory tasks in a multi-talker setting: target localization, target identification, and word recognition. The model was used to simulate psychoacoustic data from a call-sign-based listening test involving multiple spatially separated talkers [Brungart and Simpson (2007). Percept. Psychophys. 69(1), 79-91]. The main characteristics of the model are (i) the extraction of salient auditory features ("glimpses") from the multi-talker signal and (ii) the use of a classification method that finds the best target hypothesis by comparing feature templates from clean target signals to the glimpses derived from the multi-talker mixture. The four features used were periodicity, periodic energy, and periodicity-based interaural time and level differences. The model results widely exceeded probability of chance for all subtasks and conditions, and generally coincided strongly with the subject data. This indicates that, despite their sparsity, glimpses provide sufficient information about a complex auditory scene. This also suggests that complex source superposition models may not be needed for auditory scene analysis. Instead, simple models of clean speech may be sufficient to decode even complex multi-talker scenes.

Methane dissociative adsorption in catalytic steam reforming of methane over Pd/CeO2 in an electric field

To elucidate the reaction mechanism of catalytic steam reforming of methane in an electric field, operando–diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) has been used to investigate methane dissociative adsorption at low temperatures using CH4, H2O, and their isotopes. Operando-analyses demonstrated that methane was adsorbed and converted into CO and CO2 more when CD4 and/or D2O was used instead of CH4 and/or H2O. This observed “inverse” kinetic isotope effect is based on the difference of CHH vibrational energy level at the transition state. Furthermore, CO2-methanation, which is the reverse reaction of steam reforming of methane, was irreversible with H2O in an electric field. These results demonstrate that the proton collision promoted methane activation irreversibly, even at low temperatures in an electric field.

Characteristic spectra of circuit quantum electrodynamics systems from the ultrastrong- to the deep-strong-coupling regime

We report on spectra of circuit-quantum-electrodynamics (QED) systems in an intermediate regime that lies between the ultrastrong and deep-strong-coupling regimes, which have been reported previously in the literature. Our experimental results, along with numerical simulations, demonstrate that as the coupling strength increases, the spectrum of a circuit-QED system undergoes multiple qualitative transformations, such that several coupling regimes are identified, each with its own unique spectral features. The different spectral transformations can be related to crossings between energy level differences and to changes in the symmetries of the energy eigenstates. These results allow us to use qualitative spectral features to infer certain properties and parameters of the system.

Improving Visible Light-Absorptivity and Photoelectric Conversion Efficiency of a TiO2 Nanotube Anode Film by Sensitization with Bi2O3 Nanoparticles

This study presents a novel visible light-active TiO2 nanotube anode film by sensitization with Bi2O3 nanoparticles. The uniform incorporation of Bi2O3 contributes to largely enhancing the solar light absorption and photoelectric conversion efficiency of TiO2 nanotubes. Due to the energy level difference between Bi2O3 and TiO2, the built-in electric field is suggested to be formed in the Bi2O3 sensitized TiO2 hybrid, which effectively separates the photo-generated electron-hole pairs and hence improves the photocatalytic activity. It is also found that the photoelectric conversion efficiency of Bi2O3 sensitized TiO2 nanotubes is not in direct proportion with the content of the sensitizer, Bi2O3, which should be carefully controlled to realize excellent photoelectrical properties. With a narrower energy band gap relative to TiO2, the sensitizer Bi2O3 can efficiently harvest the solar energy to generate electrons and holes, while TiO2 collects and transports the charge carriers. The new-type visible light-sensitive photocatalyst presented in this paper will shed light on sensitizing many other wide-band-gap semiconductors for improving solar photocatalysis, and on understanding the visible light-driven photocatalysis through narrow-band-gap semiconductor coupling.

Energi dan Zat Gizi dalam Penyelenggaraan makanan di Taman Kanak-Kanak dan Perbandingannya terhadap Subjek Tanpa Penyelenggaraan Makanan

ABSTRACT The purpose of this study is to calculate the contribution of nutrient availability in kindergarten food service to the fulfillment of energy and nutrient requirements as well as to analyze the difference in energy and nutrient adequacy level of food consumption in a day between samples with and without food service. The study used comparative cross sectional study design with total of 80 samples that were divided into two groups by with and without food service. Consumption data of the samples were collected with a food recall method. Nutrients that meet the standards adequacy of nutrients in the menu was just calcium by 64.6% of availability. There was no difference in the level of adequacy of energy, protein, fat, carbohydrates, calcium, and vitamin C in both groups (p>0.1), but differences in the level of adequacy of iron in both groups (p 0,1), kecuali pada tingkat kecukupan zat besi (p<0,1). Kata kunci: anak TK, daya terima, ketersediaan zat gizi, pelayanan makanan, tingkat kecukupan zat gizi

Fluorescence of UV-excited LiPrP4O12 and LiTmP4O12 single crystals

Fluorescence in flux-grown single crystals of lithium praseodymium tetraphosphate (LiPrP4O12) and lithium thulium tetraphosphate (LiTmP4O12) has been studied under UV excitations with LEDs at six wavelengths between 245nm and 315nm. The emissions observed at room temperature have been assigned by means of known energy-level differences from absorptions of the same single crystals. Many more 4f–4f emissions have been found under the mentioned UV excitations compared to earlier studies with excitation wavelengths higher than 450nm. The fluorescence measurements have been used to construct the 4f energy-levels diagrams of Pr3+ and Tm3+ ions in these compounds.

Fabrication of ZnO nanowire-silicon pyramid hierarchical structure, and its self-cleaning

The transmittance diminishment of solar cells, caused by dust accumulation is higher than 52.54% every year (2006 Energ. Convers. Manage. 47 3192), which greatly reduces their overall efficiencies of power conversion. Any other strategy for improving the photovoltaic device cannot compensate for this loss caused by the dust. However, this critical issue has not received much attention. In this work, a kind of self-cleaning coating consisting of ZnO nanowire-silicon pyramid hierarchical structures is proposed to overcome the dust accumulation on the photovoltaic device. The principle of designing this self-cleaning is based on the Cassie-Baxter theory. Both the micron size effect for superhydrophobicity and the performance of anti-reflection of light of the substrate should be retained, which are the requirements of application of solar cell. The pyramid-like silicon (named silicon pyramid, hereafter) is fabricated by simple chemical etching. The effects of isopropanol, KOH, etching time, and etching temperature on the morphology of the silicon pyramid are investigated by using systematic statistical design and analysis method, to obtain the best distribution and size of the silicon pyramid. In the systematic statistical design and analysis method, the pick-the-winner rule is adopted. Eventually, we find that the optimized conditions for etching silicon pyramid (according the requirements of self-clean) are as follows: etching time is 60 min, etching temperature is 95℃, and mixture is 80 mL DI water, 2.9598 g KOH and 20 mL isopropanol. Moreover, ZnO nanowire-silicon pyramid hierarchical structures for the application of photovoltaic device are successfully hydrothermally grown on the substrate of silicon pyramid for the first time. The obtained self-cleaning coating consists of ZnO nanowire (with a diameter of 136 nm) and silicon pyramid (with a size of 8-11 m). The surface of this coating possesses superhydrophobic properties, i.e., a water contact angle of 154 and a contact angle hysteresis of less than 10, after being modified by heptadecafluorodecyltrimethoxysilane. Also, our obtained ZnO nanowire-silicon pyramid hierarchical structures have quite a good performance of anti-reflection, which appear gray in the normal environment. And the mechanism for it is postulated. Importantly, some new phenomena, such as high temperature improving the growth of silicon pyramid, are also revealed. Besides, the physical mechanism for high temperature improving the growth of silicon pyramid and anisotropic etching of silicon substrate is discussed. It is indicated that the anisotropic behavior is attributed to small difference in energy level (being a function of the crystal orientation) between the back-bond surface states. The method we proposed to achieve self-cleaning coating is versatile, reliable and low-cost, which is also compatible with contemporary micro-and nano-fabrication processes.

Simultaneous regulation of electrical and thermal transport properties in CuInTe2 by directly incorporating excess ZnX (X=S, Se)

Developing high thermoelectric performance CuInTe2 based materials is technologically and environmentally intriguing, in order to achieve this, nanoscale heterostructure barrier blocking is proposed and adopted in this work by directly incorporating excess ZnX (X=S, Se) to regulate the electrical and thermal transport properties of CuInTe2. The results prove that part of the ZnX dissolves into the CuInTe2 matrix during the hot press process while the residual ZnX acts as a nanoscale heterostructure barrier blocking for both the hole and phonon. As a consequence, three thermoelectric parameters of the CuInTe2 have been optimized simultaneously by this approach, owing to the formation of Zn- In point defects to improve carrier concentration, the concurrent hindering to the minority carriers resulting from the energy level difference between matrix and nano-heterostructure to enhance the Seebeck coefficient, and intensive phonon scattering by the nanoscale heterostructure barrier blocking to reduce the thermal conductivity. Eventually, a 90% enhanced ZT value of 1.52 has been obtained in the 6wt% ZnS added CuInTe2 sample.

Metal-Particle-Decorated ZnO Nanocrystals: Photocatalysis and Charge Dynamics.

Understanding of charge transfer processes is determinant to the performance optimization for semiconductor photocatalysts. As a representative model of composite photocatalysts, metal-particle-decorated ZnO has been widely employed for a great deal of photocatalytic applications; however, the dependence of charge carrier dynamics on the metal content and metal composition and their correlation with the photocatalytic properties have seldom been reported. Here, the interfacial charge dynamics for metal-decorated ZnO nanocrystals were investigated and their correspondence with the photocatalytic properties was evaluated. The samples were prepared with a delicate antisolvent approach, in which ZnO nanocrystals were grown along with metal particle decoration in a deep eutectic solvent. By modulating the experimental conditions, the metal content (from 0.6 to 2.3 at%) and metal composition (including Ag, Au, and Pd) in the resulting metal-decorated ZnO could be readily controlled. Time-resolved photoluminescence spectra showed that an optimal Au content of 1.3 at% could effectuate the largest electron transfer rate constant for Au-decorated ZnO nanocrystals, in conformity with the highest photocatalytic efficiency observed. The relevance of charge carrier dynamics to the metal composition was also inspected and realized in terms of the energy level difference between ZnO and metal. Among the three metal-decorated ZnO samples tested, ZnO-Pd displayed the highest photocatalytic activity, fundamentally according with the largest electron transfer rate constant deduced in carrier dynamics measurements. The current work was the first study to present the correlations among charge carrier dynamics, metal content, metal composition, and the resultant photocatalytic properties for semiconductor/metal heterostructures. The findings not only helped to resolve the standing issues regarding the mechanistic foundation of photocatalysis but also shed light on the intelligent design of semiconductor/metal composite systems to consolidate their utility in photocatalytic fields.

Effect of temperature annealing treatments and acceptors in CH3NH3PbI3 perovskite solar cell fabrication

The effects of perovskite solar cells (PSCs) using different temperature annealing treatments and various materials as an acceptor were studied, respectively. The device was composed of an indium tin oxide/poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate)/CH3NH3PbI3 (different temperature annealing treatments)/acceptor materials/bathocuproine/Ag structure. The thermal annealing treatments of CH3NH3PbI3 layers were conduct from 60 to 120 °C. The result showed that the temperature of annealing treatments have significant influences on the power conversion efficiency (PCE) of device. In addition, the acceptor materials used in the device were C60, C70 and 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI), respectively. It showed that the mechanism of PSCs is similar to the concept of organic solar cells which is the donor/acceptor interface to dissociate the electron-hole pair via the energy level difference to produce the photovoltaic effect. Furthermore, the short circuit current density and the PCE of device using C70 as acceptor is higher than that of device using C60 or PTCBI as acceptor, which is attributed to the appropriate energy level offset and higher conductivity of C70.

Architecture of the Interface between the Perovskite and Hole-Transport Layers in Perovskite Solar Cells.

The interface between the perovskite (PVK, CH3 NH3 PbI3 ) and hole-transport layers in perovskite solar cells is discussed. The device architecture studied is as follows: F-doped tin oxide (FTO)-coated glass/compact TiO2 /mesoporous TiO2 /PVK/2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-MeOTAD)/Au. After a thin layer of 4,4,4-trifluorobutylammonium iodide (TFBA) was inserted at the interface between PVK and Spiro-MeOTAD, the photovoltaic efficiency increased from 11.6-14.5 % to 15.1-17.6 %. TFBA (10 ppm) was added in the PVK solution before coating. Owing to the low surface tension of TFBA, TFBA rose to the surface of the PVK layer spontaneously during spin-coating to make a thin organic layer. The PVK grain boundaries also seemed to be passivated with the addition of TFBA. However, large differences in Urbach energies and valence band energy level were not observed for the PVK layer with and without the addition of TFBA. The charge recombination time constant between the PVK and the Spiro-MeOTAD became slower (from 8.4 to 280 μsec) after 10 ppm of TFBA was added in the PVK. The experimental results using TFBA conclude that insertion of a very thin layer at the interface between PVK and Spiro-MeOTAD is effective for suppressing charge recombination and increasing photovoltaic performances.

Exceptional Single-Molecule Transport Properties of Ladder-Type Heteroacene Molecular Wires.

A series of ladder-type fused heteroacenes consisting of thiophenes and benzothiophenes were synthesized and functionalized with thiol groups for single-molecule electrical measurements via a scanning tunneling microscopy break-junction method. It was found that this molecular wire system possesses exceptional charge transport properties with weak length dependence. The tunneling decay constant β was estimated to be 0.088 and 0.047 Å(-1) under 0.1 and 0.5 bias, respectively, which is one of the lowest β values among other non-metal-containing molecular wires, indicating that a planar ladder structure favors charge transport. Transition voltage spectroscopy showed that the energy barrier decreases as the length of the molecule increases. The general trend of the energy offsets derived from the transition voltage via the Newns-Anderson model agrees well with that of the Fermi/HOMO energy level difference. Nonequilibrium Green's function/density functional theory was used to further investigate the transport process in these molecular wires.

Measurement of the binding energy of ultracoldRb87Cs133molecules using an offset-free optical frequency comb

We report the binding energy of $^{87}$Rb$^{133}$Cs molecules in their rovibrational ground state measured using an offset-free optical frequency comb based on difference frequency generation technology. We create molecules in the absolute ground state using stimulated Raman adiabatic passage (STIRAP) with a transfer efficiency of 88\%. By measuring the absolute frequencies of our STIRAP lasers, we find the energy-level difference from an initial weakly-bound Feshbach state to the rovibrational ground state with a resolution of 5 kHz over an energy-level difference of more than 114 THz; this lets us discern the hyperfine splitting of the ground state. Combined with theoretical models of the Feshbach state binding energies and ground-state hyperfine structure, we determine a zero-field binding energy of $h\times114\,268\,135\,237(5)(50)$ kHz. To our knowledge, this is the most accurate determination to date of the dissociation energy of a molecule.

Statistical energy analysis parameter estimation for different structural junctions of rectangular plates

In industries, the use of appropriate junctions between components is of paramount interest. Coupling loss factor is one of the important parameters in statistical energy analysis for vibroacoustic analysis of complicated structures in drawing board stage. The values of coupling loss factor were calculated and compared for different junctions. The screwed and bolted junctions were examined for thin rectangular plates of same size. The energy level difference method was used to find coupling loss factors because of its simplicity. These experimentally found coupling loss factors were later compared with analytical solutions. It is noticed that the analytical results are in good agreement with experimental results. It is also observed that coupling loss factor for bolted junction are relatively high than that for screwed junction.

Improve exciton generation and dissociation by increasing fullerene content in the mixed phase of P3HT/fullerene

Designing polymeric bulk heterojunction (BHJ) morphology with good exciton separation efficiency is one of the key factors in obtaining high-efficiency polymer solar cells (PSCs). Cascaded energy formed by the energy level difference (οE) between aggregated phase and the mixed phase is thought to encourage spatial separation of the geminate charge pair. However, how the composition of the mixed phase affects the exciton generation and dissociation process is still unknown. In this paper, different amount of fullerene in the mixed phase of poly(3-hexylthiophene) (P3HT)/fullerene was achieved by changing the ratio of two fullerenes ([6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) and its bisadduct bis-PC71BM), which have different miscibility with P3HT. When the content of PC71BM increasing from 0% to about 60%, the mixed phase containing more fullerenes. More donor/acceptor (D/A) interface was formed, and the οE value also increased from 0.19eV to 0.23eV. As a result, the maximum exciton generation rate (Gmax) increased from 5.36ÿ1027m⿿3/s to 6.48ÿ1027m⿿3/s, and the exciton dissociation probabilities increased from 47% to 81%. Thus, perfect three-phase morphology for high performance solar cells was proposed, in which not only the donor and acceptor have good crystallinity to form interpenetrating network but also have good miscibility with each other to increase the fullerene content in mixed phase.

Statistical distribution of the OAM states of Bessel–Gaussian–Schell infrared beams in strong turbulent atmosphere

The effects of strong turbulence on the orbital angular momentum (OAM) states of infrared and non-diffraction beam propagation in a terrestrial atmosphere are investigated. A new probability density model for OAM states of Bessel–Gaussian–Schell beam in the paraxial and strong turbulent channel is modeled based on the modified Rytov approximation. We find that the normalization energy weight of signal OAM modes at each OAM level is approximate equivalence in strong turbulence regime, one can constitute multiple mode channels by choosing OAM modes with large energy level difference between modes to reduce mode interference, and one can utilize BGS beam with OAM modes increasing the channel capacity of optical communications.

Identifikasi Pengaruh Penambahan Ekstrak Buah Duwet(Syzygium cumini) Pada Filter Rokok Terhadap Karakter Magnetik Asap Rokok

Cigarette smoke is heterogeneous aerosol which resulted from imperfect burn of tobacco leaf that contain gas and particle component which very potential as free radical. The amount of radical content in this cigarette smoke can be reduced by bioactive compounds which functions as radical scavenger such as what is contained in the java plum ( Syzygium cumini) plant and can be identified through its magnetic character. The aim of this research was to assess and analyze magnetic character from cigarette smoke before (empty cigarette smoke) and after the addition of java plum squeeze extract to the filter (cigarette smoke of java plum) by using instrument set of ESR. This research showed that with the addition of java plum squeeze extract, it could alter magnetic character of cigarette smoke becomes more paramagnetic which seen from the difference of energy level (∆E) under the influence ofan external magnetic field, Besides the changes in the form of splitting of energy in cigarette smoke Duwet marked by changes in the value of energy groundstate more significant to the external magnetic field that is interpreted that the smoke Duwet have ferromagnetic properties more than an empty cigarette smoke.