Internal energy transfer phenomenon and light-emission properties of γ-LiAlO_2 phosphor doped with Mn^(2+)

γ-LiAlO2 phosphor was synthesized using the cellulose-citric acid sol-gel method, and its light emission and energy transfer properties were investigated. Excitation and emission spectrum analysis revealed a decrease in intensity of the spectrum as the amount of Mn2＋ doping increased. Blasse＇s equation determined the maximum distance for energy transfer between Mn2＋ ions as 4.3142 nm. Dexter＇s theory verifies that the mechanism of energy transfer between Mn2＋ ions conforms to an electric dipole and electric quadrupole interaction.

Temperature dependent direct-bandgap light emission and optical gain of Ge

Band structure, electron distribution, direct-bandgap light emission, and optical gain of tensile strained, n-doped Ge at different temperatures were calculated. We found that the heating effects not only increase the electron occupancy rate in the Γ valley of Ge by thermal excitation, but also reduce the energy difference between its Γ valley and L valley. However,the light emission enhancement of Ge induced by the heating effects is weakened with increasing tensile strain and n-doping concentration. This phenomenon could be explained by that Ge is more similar to a direct bandgap material under tensile strain and n-doping. The heating effects also increase the optical gain of tensile strained, n-doped Ge at low temperature, but decrease it at high temperature. At high temperature, the hole and electron distributions become more flat, which prevent obtaining higher optical gain. Meanwhile, the heating effects also increase the free-carrier absorption. Therefore, to obtain a higher net maximum gain, the tensile strained, n-doped Ge films on Si should balance the gain increased by the heating effects and the optical loss induced by the free-carrier absorption.

Image charge effect on the light emission of rutile TiO2(110) induced by a scanning tunneling microscope

The plasmon-enhanced light emission of rutile TiO2（110） surface has been investigated by a low-temperature scanning tunneling microscope （STM）. We found that the photon emission arises from the inelastic electron tunneling between the STM tip and the conduction band or defect states of TiO2（110）. In contrast to the Au（111） surface, the maximum photon energy as a function of the bias voltage clearly deviates from the linear scaling behavior, suggesting the non-negligible effect of the STM tip on the band structure of TiO2. By performing differential conductance （dl/dV） measurements, it was revealed that such a deviation is not related to the tip-induced band bending, but is attributed to the image charge effect of the metal tip, which significantly shifts the band edges of the TiO2（110） towards the Femi level （EF） during the tunneling process. This work not only sheds new lights onto the understanding of plasmon-enhanced light emission of semiconductor surfaces, but also opens up a new avenue for engineering the plasmon-mediated interfacial charge transfer in molecular and semiconducting materials.

Novel Field Emission Organic Light Emitting Diodes with Dynode

This work presents novel field emission organic light emitting diodes(FEOLEDs) with dynode,in which an organic EL light-emitting layer is used instead of an inorganic phosphor thin film in the field emission display(FED).The proposed FEOLEDs introduce field emission electrons into organic light emitting diodes(OLEDs),which exhibit a higher luminous efficiency than conventional OLED.The field emission electrons emitted from the carbon nanotubes(CNTs) cathode and to be amplified by impact the dynode in vacuum.These field emission electrons are injected into the multi-layer organic materials of OLED to increase the electron density.Additionally,the proposed FEOLED increase the luminance of OLED from 10 820 cd/m2 to 24 782 cd/m2 by raising the current density of OLED from an external electron source.The role of FEOLED is to add the quantity of electrons-holes pairs in OLED,which increase the exciton and further increase the luminous efficiency of OLED.Under the same operating current density,the FEOLED exhibits a higher luminous efficiency than that of OLED.

Light Emission Characteristics of Metal/Insulator/Metal and Metal/Insulator/Si Tunnel Junctions Mediated by Surface Plasmon-polaritons

The Au/Al2O3/Al metal/insulator/metal junction(MIMJ) and Au/SiO2/Si metal/insulator/Si junction(MISJ) have been constructed successfully. The light emission of these junctions was mediated by surface plasmon-polaritons(SPPs) under surface roughness. The light emission from MISJ was more uniform and stable than that from MIMJ. The light power of MISJ was about 2~3 orders higher than that of MIMJ. The light emission spectrum of MISJ was analyzed especially. In the spectrum, there was one main peak located at the wavelength of 610 nm^640 nm, which was mainly due to the couple of SPP with the surface roughness at the Au/air and Au/SiO2 interfaces. A weak peak located at the shorter wavelength region in the spectrum was also found, which was caused by the direct radiation of doped-Si plasma oscillation.

Coal Rock Condition Detection Model Using Acoustic Emission and Light Gradient Boosting Machine

Coal rock mass instability fracture may result in serious hazards to underground coal mining.Acoustic emissions(AE)stimulated by internal structure fracture should carry lots of favorable information about health condition of rock mass.AE as a sensitive non-destructive test method is gradually utilized to detect anomaly conditions of coal rock.This paper proposes an improved multi-resolution feature to extract AE waveform at different frequency resolutions using Coilflet Wavelet Transform method(CWT).It is further adopt an efficient Light Gradient Boosting Machine(LightGBM)by several cascaded sub weak classifier models to merge AE features at different views of frequency for coal rock anomaly damage recognition.The results denote that the proposed method achieves excellent recognition performance on anomaly damage levels of coal rock.It is an effective method to detect the critical stability further to predict the rock mass bursting in time.

Properties of Light Emission Spectrumof Double-barrier Tunnel Junction

Fabricated are the double-barrier light emission tunnel junctions successfully. Introduced are the fabrication process and light emission characteristics. The spectra of the junctions are measured and analyzed especially. Their spectrum wavelength including main wave peak(locates at 450 nm^500 nm) of the double-barrier junction shows a "blue shift" in comparison with that of the single-barrier Metal/Insulator/Semiconductor(MIS) or Metal/Insulator/Metal(MIM) junction(wave peak locates at 620 nm^740 nm). This phenomenon should be due to the occurrence of the electron resonant tunneling in the double-barrier junction.

Azimuthally Anisotropic Emission of Unstable Light Nuclei in Heavy Ion Collisions at Intermediate Energy

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White organic light-emitting diodes based on a combined electromer and monomer emission in doubly-doped polymers

We report on white organic light-emitting diodes （WOLEDs） based on polyvinylcarbazole （PVK） doped with 1,1-bis（（di-4-tolylamino）phenyl）cyclohexane （TAPC） and perylene, and investigate the luminescence mechanism of the devices. The chromaticity of light emission can be tuned by adjusting the concentration of the dopants. White light with the Commission Internationale de L＇Eclairage （CIE） coordinates of （0.33, 0.34） is achieved by mixing the yellow electromer emission of TAPC and the blue monomer emission of perylene from the device ITO/PVK： TAPC： perylene （100：9：1 in wt.） （100 nm）/tris-（8-hydroxyquinoline aluminum （Alq3） （10 nm）/A1. The device exhibits a maximal luminance of 3727 cd/m2 and a current efficiency of 2 cd/A.

Light-Induced Mid-Infrared Emission of Liquid Carbon Tetrachloride and Benzene

Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spectrometer is more advantageous for studying any samples, including biological samples without any damage. This technique permits obtaining unique information on the molecule structure via vibrational excitation fundamental frequencies, overtones, and combination modes. It also enables a direct observation of vibrational radiation transitions in vibrationally excited molecules as well as the channels of vibration energy redistribution, which is not allowed with any other method. In this work, the LIRES is being tested as a technique for studying of vibrationally-excited molecules of carbon tetrachloride and benzene in the liquid phase. On the other hand, using transparent liquids, we had tried to understand some of the physical phenomena that can drive emission in mid-IR. The characteristics of the infrared emission of both liquid species produced by different wavelength radiation from various types of light systems (100 - watt Xe-lamp and Nd:YAG laser;lambda = 1064 nm (8 mW) and lambda = 532 nm (4 mW)) are presented. We demonstrated that the IR-signal, as well as spectral properties of carbon tetrachloride and benzene, was dependent on the wavelength and power of excitation beam. Results obtained with different light sources show that the visible light produces a nonlinear IR-emission signal in transparent liquids. We believe that the visible light is the source of the nonlinear response and is producing the vibration excitation as well as photostimulated transformations of the molecules possessing the high activity for the nonlinear response.

Effects of Si-Layer-Thickness Ratio on UV-Light-Emission Intensity from Si/SiO<SUB>2</SUB>Multilayered Thin Films Prepared Using Radio-Frequency Sputtering

We investigated the effects of Si-layer-thickness ratios on ultraviolet (UV) peak intensities of Si/ SiO2 multilayered films produced by alternately stacking several-nanometer-thick Si and SiO2 layers using radio-frequency sputtering for the first time. The Si-layer-thickness ratio of the Si/SiO2 film is a very important parameter for enhancing the peak intensity because the ratio is concerned with the size of Si nanocrystals in the film, which might affect the intensity of the UV light emission from the film. We prepared seven samples with various estimated Si-layer-thickness ratios, and measured the photoluminescence spectra of the samples after annealing at 1150°C, 1200°C, or 1250°C for 25 min. From our experiments, we estimate that the proper Si-layer-thickness ratio to obtain the strongest UV peaks from the Si/SiO2 multilayered films is around 0.29. Such a UV-lightemitting thin film is expected to be used in future higher-density optical-disk systems.

Observation of Blue-Light Emission Band from Eu-Doped Ta₂O₅Thin Films Prepared Using Co-Sputtering

In this paper, we report on the first observation of blue-light emission bands from europium-doped tantalum pentoxide (Ta2O5:Eu) thin films prepared using a simple co-sputtering method. We prepared four specimens from one as-deposited sample, and we subsequently annealed them at 700&degC, 800&degC, 900&degC, or 1000&degC for 20 min. Four remarkable photoluminescence (PL) peaks at wavelengths of 600, 620, 650, and 700 nm due to the 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transitions of Eu3+ were observed from all the specimens, and blue PL peaks around a wavelength of 450 nm were also observed from the specimens annealed at 800&degC, 900&degC, and 1000&degC. The blue PL peaks seem to be originated from the 4f65d1→4f7 transition of Eu2+. Both Eu3+ and Eu2+ ions seem to exist in our Ta2O5:Eu co-sputtered thin films annealed at temperatures from 800&degC to 1000&degC. Such Ta2O5:Eu co-sputtered thin films seem to be used as multi-functional coating films having both anti-reflection and down-conversion effects for realizing high-efficiency silicon solar cells.

Observation of Violet-Light Emission Band for Thulium-Doped Tantalum-Oxide Films Produced by Co-Sputtering

We prepared thulium-doped tantalum (V) oxide (Ta2O5:Tm) thin films using co-sputtering of two Tm2O3 pellets and a Ta2O5 disc, and we observed photoluminescence (PL) peaks not only around a wavelength of 800 nm due to the 3H4→3H6 transition of Tm3+ but also around a wavelength of 400 nm (violet) from the films after annealing for the first time. Comparatively narrow PL peaks around the wavelength of 400 nm were observed from the films annealed at 800°C and 900°C for 20 min. The peak intensity from the film annealed at 900°C was approximately four-times stronger than that from the film annealed at 800°C. The origin of the 400-nm peaks seems to be the same as our non-doped Ta2O5 thin films deposited using radio-frequency sputtering because we observe PL peaks around 400 - 430 nm from the Ta2O5 films. Such a Ta2O5:Tm co-sputtered thin film seems to be used as a multi-functional coating film having both anti-reflection and down-conversion effects for realizing a high-efficiency silicon solar cell.

Study on preparation and application performance of blue sky rare earth light storage and emission material

Under reduction atmosphere, a blue sky rare earth silicate light storage and emission material was prepared by high temperature solid phase synthesis. The best constituent ratio of this material was determined through orthogonal experiment, and its excitation and emission spectra and X-ray diffraction patterns were measured. And a comparative study was conducted on its application properties.

Combined optical fiber interferometric sensors for the detection of acoustic emission

A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.

Emission of High Energy during Super-Compressibility of Supersonic Jets

New source of light emission of high energy is found due to arising of instability in supersonic jets. These phenomena are observed in gas jets flowing from the nozzle with a central cone. It leads to high accelerations of the molecules, ions and elementary particles. The emission spectra of the jets are obtained. Decoding of the spectra allowed us to define inverted population of rotational and vibrational levels, electrons temperature, rotational and vibrational temperatures for molecular ions. Internal energy decreasing provides the instability and gas volume decreasing due to internal forces;super-compressibility is result of it;its produce high density of light energy emission in various continuous media.

Disappearance of Superconductivity and a Concomitant Lifshitz Transition in Heavily Overdoped Bi_2Sr_2CuO_6 Superconductor Revealed by Angle-Resolved Photoemission Spectroscopy

By partially doping Pb to effectively suppress the superstructure in single-layered cuprate Bi_2Sr_2CuO_(6+δ)(Pb-Bi2201) and annealing them in vacuum or in high pressure oxygen atmosphere, a series of high quality Pb-Bi2201 single crystals are obtained with T_c covering from 17 K to non-superconducting in the overdoped region. High resolution angle resolved photoemission spectroscopy measurements are carried out on these samples to investigate the evolution of the Fermi surface topology with doping in the normal state. Clear and complete Fermi surfaces are observed and quantitatively analyzed in all of these overdoped Pb-Bi2201 samples. A Lifshitz transition from holelike Fermi surface to electron-like Fermi surface with increasing doping is observed at a doping level of ~0.35. This transition coincides with the change that the sample undergoes superconducting-to-non-superconducting states.Our results reveal the emergence of an electron-like Fermi surface and the existence of a Lifshitz transition in heavily overdoped Bi2201 samples. This provides important information in understanding the connection between the disappearance of superconductivity and the Lifshitz transition in the overdoped region.

White Organic Light Emitting Devices Based on Multiple Emissive Nanolayers

In this paper,a white organic light-emitting device(WOLEDs) with multiple-emissive-layer structure has been fabricated.The device has a simple structure of indium tin oxide(ITO)/NPB(20 nm)//DPVBi(20 nm)/CDBP:x Ir(btp)2acac(10 nm)/Alq3(25 nm)/BCP(5 nm)/Cs F(1 nm)/Al(150 nm)(x= 0.15,2.5 and 3.0 wt%),where NPB and BCP are used as the hole-injecting layer,electron transporting and hole blocking layer,respectively.White light emission was realized in an OLED with 2.5% Ir(btp)2acac doping concentration.The device exhibits peak efficiency of 1.93 cd/A at 9 V and maximum brightness of 7005 cd/m^2 at 14 V.The Commission International de I'Eclairage(CIE)(1931) coordinates of white emission are well within the white zone,which moves from(0.35,0.33) to(0.26,0.30) when the applied voltage is varied from 5 V to 14 V.

Energy Conversion Mechanics for Photon Emission per Non-Local Hidden-Variable Theory

Problem-Energy conversion processes in optical phenomena are incompletely explained by wave theory or quantum mechanics. There is a need for ontologically rich explanations at the level of individual particles. Purpose: This paper reports on the application of a non-local hidden-variable solution called the Cordus theory to this problem. The method is directed to the systematic development of a conceptual framework of proposed causal mechanisms. Findings: It has long been known that the bonding commitments of the electron affect its energy behaviour but the mechanisms for this have been elusive. We show how the degree of bonding constraint on the electron determines how it processes excess energy. A key concept is that the span and frequency of the electron are inversely proportional. This explains why energy changes cause positional distress for the electron. Natural explanations are given for multiple emission phenomena: Absorbance;Saturation;Beer-Lambert law;Colour;Quantum energy states;Directional emission;Photoelectric effect;Emission of polarised photons from crystals;Refraction effects;Reflection;Transparency;Birefringence;Cherenkov radiation;Bremsstrahlung and Synchrotron radiation;Phase change at reflection;Force impulse at reflection and radiation pressure;Simulated emission (Laser). Originality: The paper elucidates a mechanism for how the electron responds to combinations of bonding constraint and pumped energy. The crucial insight is that the electron size and position(s) are coupled attributes of its frequency and energy, where the coupling is achieved via physical substructures. The theory is able to provide a logically coherent explanation for a wide variety of energy conversion phenomena.

Tunable emission of cadmium-free transition metal(Cu, Mn, Ag) co-doped ZnInS/ZnS core-shell quantum dots

Color tunable quantum dots（QDs） based on the Cu, Mn, Ag co-doped Zn In S core and Zn S outer-shell were synthesized by using an eco-friendly method. Core-shell doped QDs with the average size of 3.85 nm were obtained by using a one-pot synthesis followed by a hot injection with n-dodecanethiol（DDT） and oleylamine（OLA） as stabilizers in oil phase. Cu, Mn and Ag ions were introduced as single-dopant or co-dopants during the synthesis, providing an effective means to control the emission color of the QDs. The as-synthesized QDs showed photoluminescence emission ranging from green（530 nm） to near-red（613 nm）, adjusted by doping components, dopant concentration, and Zn/In ratio. Importantly, quasi-white emission has been achieved by controlling the concentration of co-doped metal ions（Mn, Cu and Ag）. The primary results demonstrated the promising potential of co-doped QDs as alternative materials for future high quality white LED applications.