Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium

By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode tield in a Kerr-like medium. The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account.

Characteristics of emissive spectrum and the removal of nitric oxide in N_2/O_2/NO plasma with argon additive

Although the approach using non-thermal plasma（NTP） for deNOx has been studied for over 15 years,how to achieve higher removal effciency with lower cost is still a barrier for its industrial application.In order to investigate the impact of the argon additive on electron density,energy and nitric oxide reduction process in plasma,the spectrum of the dielectric barrier discharge at atmospheric pressure in a coaxial reactor was measured using the monochromater with high resolution.The comparative experiments for NO reduction were carried out simultaneously in N2/O2/NO plasma stream with and without argon,respectively.The nitrogen molecular spectrum which is attributed to the energy level transition（C^3πu→ B^3πg） was compared in the wavelength range 300-480 nm and the electron density and temperature were determined based on the relative intensities and Stark broadening width of spectral lines.The spectrum results indicated that the argon additive could enhance the intensity of emissive spectrum of plasma,thus the electron concentration as well as the energy was increased,and finally prompted the ionization rate to produce active N,O and O3.The results of NO reduction showed that NO conversion effciency increased in the range of 10%-30% with 5% addition of argon in stream comparing with the condition without argon additive.This study will play a positive role in the industrial application of dielectric barrier discharge deNOx reactor.

Formation Mechanism and Emission Spectrum of AlO Radicals in Reaction of Laser-ablated Al Atom and Oxygen

The emission spectrum of AlO radicals was analyzed in 440-540 nm in the reaction of laser ablated Al beam and O 2. The carrier of spectrum was assigned to Δ ν =0, ±1, ±2 vibrational sequences of B 2Σ +-X 2Σ + transition of AlO radicals, the observed maximum vibrational quantum number was ν ′=6. The rotational and vibrational temperatures of B state were estimated at 3000 and 7500 K by spectrally simulating the rovibronic population distribution. There is a strong evidence that the production of excited Al( 2 S ) atoms is essential to the formation of excited AlO radicals.

Effect of cavity dissipation on the emission spectrum of an atom interacting with a field in the dispersive approximation

The emission spectrum of a two-level atom interacting dispersively with a single mode radiation field in the dissipative cavity is investigated. A general expression for the emission spectrum is derived. The numerical results for the initial field in coherent state are calculated. It is found that the spectrum structure is influenced significantly by the cavity damping constant k, and the spectrum structure is dependent on the interaction time r when the cavity dissipation is present. Only one peak located at wa appears in the atomic spectra for larger T.

Continuous Emission Spectrum Measurement for Electron Temperature Determination in Low-Temperature Collisional Plasmas

Continuous emission spectrum measurement is applied for the inconvenient diagnos- tics of low-temperature collisional plasmas. According to the physical mechanism of continuous emission, a simplified model is presented to analyze the spectrum in low temperature plasma. The validity of this model is discussed in a wide range of discharge parameters, including electron tem- perature and ionization degree. Through the simplified model, the continuous emission spectrum in a collisional argon internal inductively coupled plasma is experimentally measured to determine the electron temperature distribution for different gas pressures and radio-frequency powers. The inverse Abel transform is also applied for a better spatially resoluted results. Meanwhile, the result of the continuous emission spectrum measurement is compared to that of the electrostatic double probes, which indicates the effectiveness of this method.

Emission spectrum of a harmonically trapped Λ-type three-level atom

We theoretically investigate the emission spectrum for a A-type three-level atom trapped in the node of a standing wave. We show that the atomic center-of-mass motion not only directly affects the peak number, peak position, and peak height in the atomic emission spectrum, but also influences the effects of the cavity field and the atomic initial state on atomic emission spectrum.

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.

Extreme ultraviolet spectral characteristic analysis of highly charged ions in laserproduced Cu plasmas

This paper reports the results of spectral measurements and a theoretical analysis of the temporal and spatial evolution of laser-produced Cu plasma in vacuum in the range of 8–14 nm.The time dependence of the extreme ultraviolet band spectrum at different positions near the target surface was obtained and found to be dominated by three broad-band features.The 3p and 3d excitations of Cu5+–Cu9+ions were calculated using the Hartree–Fock theory with configuration interactions.The characteristics of the spectral line distribution for the 3p–nd and 3d–nf transition arrays were analyzed.Based on the steady-state collisional radiation model and the normalized Boltzmann distribution,the complex spectral structure in the band of 13–14 nm is accurately explained through consistency comparisons and benchmarking between the experimental and theoretical simulation spectra,demonstrating that the structure mainly stems from the overlapping contribution of the 3d–4f and 3p–3d transition arrays for the Cu5+–Cu9+ions.These results may help in studying the radiation characteristics of isoelectronic series highly-charged ions involving the 3d excitation process.

Emission Spectra and Crystallographic Sites of Eu^(2+) in Ca_8Zn(SiO_4)_4Cl_2

The fluorescent characteristic and emission spectra of Eu^(2+) in the cubic structure Ca_8Zn(SiO_4)_4Cl_2 with three kinds of cation sites is reported.The influence of temperature,Eu^(2+) concentra- tion and excitation conditions on fluorescent properties of Eu^(2+) are studied at 77 and 298 K.The coordination number of Eu^(2+) at different sites is obtained.The green and red emission bands arise from Eu_(2+) ions locating on eight- and six- coordinated inequivalent sites respectively.

Characteristics of a large gap uniform discharge excited by DC voltage at atmospheric pressure

A large-gap uniform discharge is ignited by a coaxial dielectric barrier discharge and burns between a needle anode and a plate cathode under a low sustaining voltage by feeding with flowing argon. The basic aspects of the large-gap uniform discharge are investigated by optical and spectroscopic methods. From the discharge images, it can be found that this discharge has similar regions with glow discharge at low pressure except a plasma plume region. Light emission signals from the discharge indicate that the plasma column is invariant with time, while there are some stochastic pulses in the plasma plume region. The optical emission spectra scanning from 300 nm to 800 nm are used to calculate the excited electron temperature and vibrational temperature of the large-gap uniform discharge. It has been found that the excited electron temperature almost keeps constant and the vibrational temperature increases with increasing discharge current. Both of them decreases with increasing gas flow rate.

Nanosecond Repetitively Pulsed Dielectric Barrier Discharge in Air at Atmospheric Pressure

Dielectric barrier discharge （DBD） between two cylindrical glass containers with salt water generated by a nanosecond repetitively pulsed power generator is reported. The electrical parameters, luminous images and spectrum diagnosis are presented. It is shown that the DBD possesses a large discharge current and an intense optical emission from the nitrogen second positive system below 400 nm. The gas temperature remains very close to room temperature regardless of pulse polarity. Luminous photographs with a short exposure time down to 2 ns indicate that no filament is observed and the discharge is homogeneous.

Analysis of Dynamic Tensile Process of Fiber Reinforced Concrete by Acoustic Emission Technique

The fiber reinforced concrete has good dynamic mechanical properties. But corresponding research lacks the dynamic damage characteristics of the polypropylene fiber（fiber of low elastic modulus） and steel fiber（fiber of high elastic modulus） reinforced concrete under medium strain rate（10-6 s-1-10-4 s-1）. In order to study the effect of strain rate on the damage characteristics of fiber reinforced concrete during the full curve damage process, the real time dynamic acoustic emission（AE） technique was applied to monitor the damage process of fiber reinforced concrete at three strain rates. The AE wavelet energy spectrum in ca8 frequency band and average AE peak frequency at three strain rates were analyzed. With the accumulation of damage, the AE wavelet energy spectrum in ca8 frequency band increased first and then decreased, and the average AE peak frequency increased gradually. With the increase of strain rate, the AE wavelet energy spectrum in ca8 frequency band and average AE peak frequency decreased gradually. The polypropylene fiber content has more obvious effect on the Dynamic increase factor（DIF） of the peak stress than the steel fiber content. The theoretical basis was provided for the monitoring of dynamic damage of fiber reinforced concrete based on the AE technique.

Luminescent Properties of Tb^(3+) Doped CaMoO_4 Phosphor for UV White Light Emitting Diode

A novel yellowish green phosphor Tb3+ doped calcium molybdate (CaMoO4) was synthesized at 800 ℃ by conventional solid state reaction method and their crystal structure and luminescent properties were investigated. The X-ray diffraction patterns (XRD) showed that they were simple crystalloid of CaMoO4∶Tb3+. Monitored at 550 nm, the excitation spectrum consisted of two bands and the two excitation peaks located at 305 and 380 nm respectively. The emission spectrum excited by 380 nm UV light was composed of four narrow bands. The strongest emission was located at 540 nm corresponding to 5D4-7F5 transition. The appropriate concentration of Tb3+ was 5%(mole fraction) for the highest emission intensity at 550 nm. These results showed that this Tb3+-activated CaMoO4 was a promising yellowish green phosphor for near-ultraviolet (NUV) InGaN-based white LED.

Study on Ca_8Mg(SiO_4)_4Cl_2:Eu^(2+) Doped with Sr^(2+)

Ca8Mg(SiO4)4Cl2:Eu2+ phosphor doped with Sr2+ cation for Ca2+ partially, was synthesized by solid-slate reaction at high temperature under reducing atmosphere, and its luminescent properties were investigated. The experimental results indicate that the emission intensity of the phosphor increases after being doped with a few amount of Sr2+ ion. The emission peak of the phosphor blue shift to about 464 nm when the phosphor is doped with large quantity of Sr2+ ions. The excitation spectrum indicates that the phosphor can be well excited by UV and blue light from 300 to 460 nm, and the phosphor was fitted well for the excitation by UV or blue-LED.

Electric and plasma characteristics of RF discharge plasma actuation under varying pressures

The electric and plasma characteristics of RF discharge plasma actuation under varying pressure have been inves- tigated experimentally. As the pressure increases, the shapes of charge-voltage Lissajous curves vary, and the discharge energy increases. The emission spectra show significant difference as the pressure varies. When the pressure is 1000 Pa, the electron temperature is estimated to be 4.139 eV, the electron density and the vibrational temperature of plasma are /peak /lPeak which describes the electron temper- 4.71 x 10^11 cm-3 and 1.27 eV, respectively. The ratio of spectral lines ＂391.4/＇380.5 ature hardly changes when the pressure varies between 5000-30000 Pa, while it increases remarkably with the pressure below 5000 Pa, indicating a transition from filamentary discharge to glow discharge. The characteristics of emission spec- trum are obviously influenced by the loading power. With more loading power, both of the illumination and emission spectrum intensity increase at 10000 Pa. The pin-pin electrode RF discharge is arc-like at power higher than 33 W, which results in a macroscopic air temperature increase.

Photosynthetic Characteristics of Flag Leaves in Rice White Stripe Mutant 6001 During Senescence Process

Physiological, biochemical and electron microscopy analyses were used to investigate the photosynthetic performance of flag leaves in rice white stripe mutant 6001 during the senescence process. Results showed that the chlorophyll content at the heading and milk-ripe stages in rice mutant 6001 were about 34.78% and 3.00% less than those in wild type 6028, respectively. However, the chlorophyll content at the fully-ripe stage in rice mutant 6001 was higher than that in wild type 6028. At the heading stage, the net photosynthetic rate （Pn） in rice mutant 6001 was lower than that in wild type 6028. Rice mutant 6001 also exhibited a significantly slower decrease rate of Pn than wild type 6028 during the senescence progress, especially at the later stage. Furthermore, Ca2^-ATPase, Mg~^-ATPase and photophosphorylation activities exhibited the similar trends as the Po. During the senescence process, the 68 kDa polypeptide concentrations in the thylakoid membrane proteins exhibited a significant change, which was one of the critical factors that contributed to the observed change in photosynthesis. We also observed that the chloroplasts of rice mutant 6001 exhibited higher integrity than those of wild type 6028, and the chloroplast membrane of rice mutant 6001 disintegrated more slow during the senescence process. In general, rice mutant 6001 had a relatively slower senescence rate than wild type 6028, and exhibited anti-senescence properties.

Multi-scale morphology analysis of acoustic emission signal and quantitative diagnosis for bearing fault

Monitoring of potential bearing faults in operation is of critical importance to safe operation of high speed trains.One of the major challenges is how to differentiate relevant signals to operational conditions of bearings from noises emitted from the surrounding environment.In this work,we report a procedure for analyzing acoustic emission signals collected from rolling bearings for diagnosis of bearing health conditions by examining their morphological pattern spectrum（MPS） through a multi-scale morphology analysis procedure.The results show that acoustic emission signals resulted from a given type of bearing faults share rather similar MPS curves.Further examinations in terms of sample entropy and Lempel-Ziv complexity of MPS curves suggest that these two parameters can be utilized to determine damage modes.

Electrical and Optical Characteristics of Electrodeless Lamp

In order to study the methods to enhance the efficacy of electrodeless lamp,volt-ampere characteristics,illuminance and emission spectrum have been investigated in home-built electrodeless lamp experimental system with an electrodeless lamp in shape like QL 85 lamp.The results show that lamp current increases as lamp voltage increases in non-discharge,the current decreases first and then increases as the voltage increases in discharge.The illuminance of electrodeless lamp increases linearly with discharge power increasing,and it decreases linearly with power decreasing.The emission spectrum is different for different bulb and lighting time.The spectrum of Ar 811.5 nm,76.5 nm,750.4 nm and Hg 313.2 nm decrease with lighting time.While the intensity of Hg 407.8 nm increases with lighting time.

Luminescent Properties of Ce^(3+) Ions in Zinc Phosphate Glass Prepared in Air

Glasses are prepared by sintering P2O5, ZnO and Ce2（C2O4）3 10H2O mixtures at 1 100 ℃ in air and then annealed at 400 ℃ for 10 hours. The obtained glasses are homogeneous, transparent and colorless. Emission and excitation spectra are measured for the samples and the results show that the glasses contain Ce3＋ trivalent cerium ions. The parameters of glass preparation obtained here may be adapted to preparing this type of glasses doped with other lanthanide ions, so as to study energy transfer phenomena and variation of radiative lifetime with refractive index due to local field effect.

Experimental Studies of Low-Pressure Plasma Jet by Means of Langmuir Probes and Emission Spectra

An investigation was made into the argon plasma jet that expanded in a low-pressure vacuum chamber. The spatial distributions of the parameters of the plasma jet with different supplied powers were measured using a ten-channel Langmuir probe array. The chemical species in the plasma jet were identified by emission spectroscopy. The electron excitation temperatures at two positions, 10 cm and 50 cm downstream from the nozzle exit were calculated, respectively, by the Boltzmann plot method.