Emission spectra of microwave plasma and MPCVD transparent diamond film

The emission spectra of microwave plasma was in line measured in visible light wave band using a self made optical fiber spectrometer, the change rule of the atomic hydrogen ( H ) and double carbon radical( C 2) was given under different CH 4/H 2 ratios of volume flow. The effect of atomic hydrogen ( H ) on CVD diamond, deposited high quality and transparent diamond film by microwave plasma CVD (MPCVD) was analyzed according to the measured results by scanning electron microscopy(SEM), laser Raman spectrometry(Raman), and Fourier transform infrared spectrometry(FTIR). The results showed that the diamond film consisted of (220) orientation and it was homogeneous, compact, low defective, high quality film, its infrared transmissibility was about 70%, approached theoretical transmissibility of diamond. It was key conditions that a large number of atomic hydrogen ( H γ ) and double carbon radical( C 2) exist in the course of high quality diamond film growth. The research provided a rapid method for technology exploration of microwawe plasma CVD, and a reliable basis for research on growth mechanism of diamond film.

Applications of Wigner high-order spectra in feature extraction of acoustic emission signals

The characteristics of typical AE signals initiated by mechanical component damages are analyzed. Based on the extracting principle of acoustic emission(AE) signals from damaged components,the paper introduces Wigner high-order spectra to the field of feature extraction and fault diagnosis of AE signals. Some main performances of Wigner binary spectra,Wigner triple spectra and Wigner-Ville distribution (WVD) are discussed,including of time-frequency resolution,energy accumulation,reduction of crossing items and noise elimination. Wigner triple spectra is employed to the fault diagnosis of rolling bearings with AE techniques. The fault features reading from experimental data analysis are clear,accurate and intuitionistic. The validity and accuracy of Wigner high-order spectra methods proposed agree quite well with simulation results. Simulation and research results indicate that wigner high-order spectra is quite useful for condition monitoring and fault diagnosis in conjunction with AE technique,and has very important research and application values in feature extraction and faults diagnosis based on AE signals due to mechanical component damages.

Discharge Modes Suggested by Emission Spectra of Nitrogen Dielectric Barrier Discharge with Wire-Cylinder Electrodes

In this paper,nitrogen dielectric barrier discharge（DBD） plasma was generated in a quartz tube with coaxial wire-cylinder electrodes at atmospheric pressure.By varying the nitrogen gas flow（FN） in the range of 0-1 m3/h,the plasma optical emission spectra（OES） were measured and studied.The vibration（T_（vib）） and rotation temperature（T_（rot）） of nitrogen were obtained,by fitting the rovibronic bands of N_2（C^3∏_u-B^3∏_g,0-1）,and by the Boltzmann plot method for purposes of comparison.T_（vib） increased up to 2481 K with increasing nitrogen flow till0.2 m3/h,and then decreased with further increasing FN,while Trot decreased monotonously and approached to-350 K for FN ≥ 0.6 m^3/h.The intensity of N_2（C^3∏_u-B^3∏_g,0-0,1-0,0-3） and N_2~＋（B^2∑_u~＋-X^2Σ_g~＋,0-0） exhibited similar evolution with increasing FN to those of the T_（vib） and Trot,respectively.The discharge photos revealed that the discharge filaments gradually decreased with increasing FN,and eventually disappeared,which implied that a discharge mode transition emerged with increasing FN.The possible mechanism for the discharge mode transition is studied in detail according to the vibration（T_（vib）） and rotation temperature（T_（rot）） of nitrogen.

P-branch emission spectra of the A^1π-X^1Σ^+ system of IrN

The P-branch emission spectra of （4,1） and （3,1） bands of the A^1П-X^1∑^＋ system of IrN molecule are studied using an analytical formula which is derived from elementary expression of molecular total energy by taking multiple spectral differences. It not only reproduces the known experimental transition lines, but also predicts the unknown spectral lines up to J = 80 for each band by using a group of fifteen known experimental transition lines.

Electrical characters and optical emission spectra of VBD coupled SBD excited by sine AC voltage in atmospheric air

In this paper,volume coupled surface barrier discharge（V-SBD） with three structures possessing different volumes is excited by sine AC power in atmospheric air.Discharge images,waveforms of applied voltage and discharge current,and optical emission spectra simulating rotational and vibrational temperatures are recorded and analyzed.The effects of applied voltage on emission intensities of N2（C^3Πu→ B^3Πg） and N2^＋（B^2∑u^＋ → X^2Eg^＋）,and rotational and vibrational temperatures are investigated.The results show that as applied voltage rises,emission intensities and rotational temperatures increase while vibrational temperatures decrease.In addition it is found that,as applied voltage varies,the rotational temperature of surface discharge changes faster than that of volume discharge.

Volume added surface barrier discharge plasma excited by bipolar nanosecond pulse power in atmospheric air: optical emission spectra influenced by gap distance

In this paper, volume barrier discharge with different gap distances is added on the discharge border of high-voltage electrode of annular surface barrier discharge for generating volume added surface barrier discharge （V-SBD） excited by bipolar nanosecond high-voltage pulse power in atmospheric air. The excited V-SBDs consist of surface barrier discharge （d = 0 mm） and volume added surface barrier discharges （d = 2 mm and 3 mm）. The optical emission spectra are recorded for calculating emission intensities of N2 （C3 ∏u → B3∏g） and N2＋ （B2 ∑u＋ → X2 ∑g＋）, and simulating rotational and vibrational temperatures. The influences of gap distance of V-SBD on emission intensity and plasma temperature are also investigated and analyzed. The results show that d = 0 mm structure can excite the largest emission intensity of N2 （C3 ∏u → B3 ∏g）, while the existence of volume barrier discharge can delay the occurrence of the peak value of the emission intensity ratio of N2 ＋ （B2 ∑u＋ → X2 ∑＋g）/N2 （C3 ∏u → B3 ∏g） during the rising period of the applied voltage pulse and weaken it during the end period. The increasing factor of emission intensity is effected by the pulse repetition rate. The d = 3 mm structure has the highest threshold voltage while it can maintain more emission intensity of N2 （C3 ∏u→ B3∏g） than that of d = 2 mm structure. The structure of d = 2 mm can maintain more increasing factor than that of the d = 3 mm structure with varying pulse repetition rate. Besides, the rotational temperatures of three V-SBD structures are slightly affected when the gap distance and pulse repetition rate vary. The vibrational temperatures have decaying tendencies of all three structures with the increasing pulse repetition rate.

Blue-shift of Nano-Y_2O_3 : Eu^(3+) Emission Spectra Excited by X-ray

Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomena exist in the nano-Y2O3:Eu3+ emission spectra excited by X-ray. The wave lengths of the peak (5D0→7F2) are related with the grain size of the powder

Motion Characteristics of Single Electrons of Atoms of Atomic Gas of Hydrogen and Single Electrons of Hydrogen-Like Ions in Form Gas or Vapour during Decays of Such Atoms and Ions. Emission Line Spectra

For the first time the vector differential equation of central motion of single electron in electric field of an atomic nucleus as in external central electric field is set up and solved. Here the following findings are reported. Each of single electrons of a part of atoms of atomic gas of hydrogen and a part of hydrogen-like ions in the form of a gas or a vapour revolves around corresponding atomic nucleus in a flat spiral which has an interior maximum of turns density. The distance between each of these single electrons and corresponding atomic nucleus increases while a speed of single electron decreases. Such motion of single electrons takes place with no expenditures of external energy and points to decays of foregoing parts of atoms and ions. The electric field strength of the atomic nuclei of atoms of atomic gas of hydrogen and hydrogen-like ions in the form of a gas or a vapour is inversely proportional to the distance between the atomic nucleus and the corresponding single electron by greater than the power of 3. Calculated cyclic frequency (rough value 3.5×1014 s-1) of revolution of the electron around the nucleus of atom of atomic gas of hydrogen (in interior maximum of turns density of the flat spiral), which moves at speed 2.2×106 ms-1, and central cyclic frequency of α-line of Balmer series (4.5×1014 s-1) have the same order of magnitude. This fact and line structure of experimental emission line spectra confirm the formation of all lines of these spectra by continuous slight emission of light front by single electrons. The formation of series of lines of emission line spectra is linked to repeated creations of atoms of atomic gas of hydrogen and hydrogen-like ions in the form of a gas or a vapour.

Diagnostics of laser-induced plasma on carbon-based polymer material using atomic and molecular emission spectra

Time-integrated optical emission analysis of laser-induced plasma on Teflon is presented.Plasma was induced under atmospheric pressure air using transversely excited atmospheric CO_(2) laser pulses.Teflon is a C-based polymer that is,among other things,interesting as a substrate for laser-induced breakdown spectroscopy analysis of liquid samples.This study aimed to determine the optimal experimental conditions for obtaining neutral and ionized C spectral lines and C2 and CN molecular band emission suitable for spectrochemical purposes.Evaluation of plasma parameters was done using several spectroscopic techniques.Stark profiles of appropriate C ionic lines were used to determine electron number density.The ratio of the integral intensity of ionic-to-atomic C spectral lines was used to determine the ionization temperature.A spectral emission of C2 Swan and CN violet bands system was used to determine the temperature of the colder,peripheral parts of plasma.We critically analyzed the use of molecular emission bands as a tool for plasma diagnostics and suggested methods for possible improvements.

Intense up-conversion emissions of yb3＋/Dy3＋ co-doped A12O3 nanopowders prepared by non-aqueous sol-gel method＊

yb3＋/Dy3＋ co-doped A1203 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to 4C9/2→ 6H13/2, 4C9/2→ 6Hll/2, 4115/2 → 6H13/2, and 4F9/2 →6Hll/2 transitions of Dy3＋, respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3＋ and Dy3＋ is discussed.

Study of Non-Thermal DC Arc Plasma of CH_4/Ar at Atmospheric Pressure Using Optical Emission Spectroscopy and Mass Spectrometry

Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmospheric-pressure DC arc discharge generator in CH_4/Ar were investigated.The voltage-current characteristics were measured for different CH_4/Ar ratios.Optical emission spectroscopy was employed to analyze the electron excitation temperature,gas temperature and electron density under various discharge conditions.The hydrocarbon molecules produced in the CH4/Ar plasmas were detected with photoionization mass spectrometry.The optical spectral results demonstrated that the electron excitation temperature was 0.4-1 eV,the gas temperature was 2800-4200 K and the electron density was in the range of（5-20）×10^15 cm^-3.The mass spectrum indicated that a variety of unsaturated hydrocarbons（C2H4,C3H6,C6H6,etc.） and several highly unsaturated hydrocarbons（C4H2,C5H6,etc.） were produced in the non-thermal arc plasmas.

Temporally-Resolved Emission Spectroscopic Diagnostics of the Atmospheric Pressure Glow Discharge in Helium

Temporally-resolved spectroscopic diagnostics of dielectric barrier discharges （DBDs） in atmospheric-pressure helium was carried out to study the discharge mechanism. Using an intensified charge-coupled device （ICCD） and a grating spectrometer, we obtained the emission spectra of homogeneous discharges and presented them in 3D graphs. We also studied the time variation of typical emissions from He, 0 and first negative bands of N＋_2. The results showedthat the spectral lines do not develop synchronously as-N_2（B_2∑U＋x2∑＋G,0～0,λ=391.4nm）and N＋2（B2∑＋u→X2∑＋g,0～1,λ=427.8nm） appear earlier and last for a longer time than He（3_3S1→2_3P1,λ=706.5nm）and O （3_P→3_5S,λ=777.4nm） A certain number of He metastables produced in the initial stage of discharge. Even between adjacent pulses, the emissions from N＋2 can still keep certain intensities while those from He and 0 extinguish. Since long-lifetime Hemetastables are produced and exist in the discharging space, it is the Penning ionization thatkeeps the long decay of N＋ emissions.

Granite deformation and behavior of acoustic emission sequence under the temperature and pressure condition at different crust depths

Results of triaxial compression experiment results show that granite rock strength increases with the depth until 30 km. In shallow crust, rock failure exhibits abrupt or quasi-abrupt instability under lower pressure. Acoustic Emission (AE for short) distributed almost uniformly before and after failure. Go through downwards into the depth range with progressive failure feature, there are no or only a few number of AE before and after failure. In deeper range, rock failure shows some feature of quasi-abrupt instability under high pressure. There are still few AE before failure, but with the stick-slip, much more An events were detected after failure. Under the temperature and pressure condition of more deep crust (about 26 km), rock failure takes abrupt instability under high pressure as main feature, there are dense AE activities before failure and cumulated frequency of AE increases exponentially before the failure. In about 35 km depth range, rock strength decreases quickly with the depth and sample exhibits semi-ductile or ductile progressive fails, there are no AE being detected before and after failure. The b value of AE sequence before failure seems a little smaller than that after failure, and b value roughly decreased with depth. The numerical range of index α is the widest in about 18 km depth and becomes narrow in the condition of more shallow or more deep crust. So, when the temperature and pressure condition simulating the real environment of focal depth changes from shallow to deep in the crust, the range of a of microfracture sequence would undergo such an evolvement process that a changes from narrow to wide and then to narrow again.

Anisotropic stimulated emission cross-section measurement in Nd:YVO_4

As a crucial parameter in the design and analysis of laser performances, stimulated emission(SE) cross-section is currently considered to be dependent on several factors, such as temperatures and eigen-polarizations for anisotropic crystals. In contrast with these factors, impact of propagating directions upon SE cross-section has garnered less attention.In this paper, to investigate the SE cross-section in arbitrary propagating directions, fluorescence spectra for the transition ~4F_(3/2)→~4I_(11/2) in Nd:YVO_4 are measured in different propagating directions. Based on Fuchtbauer–Ladenburg equation model, the propagating direction-dependent SE cross-section spectra in Nd:YVO_4 are obtained for the first time, to our best knowledge. A novel concept of anisotropic SE cross-section is proposed to interpret the propagating direction-dependent effect. The experiment results reveal that for an arbitrary propagating direction the SE cross-section of e light around 1064 nm can be expressed as a superposition from two principle axial propagating directions with a weight of plane projection.

Spontaneous emission fromΛ-type three-level atom driven by bichromatic field in anisotropic double-band photonic crystals

The spontaneous emission property ofΛ-type three-level atom driven by the bichromatic field in the anisotropic double-band photonic crystal is calculated by n-times iteration method.The influence of different parameters on atomic spontaneous emission is studied,and the phenomena of atomic spontaneous emission are explained in the dressed state representation.It is found that the spontaneous emission spectra of the atom driven by the bichromatic field presents a multi-peak comb structure.The position of the emission peak is determined by the initial state of the atom,and the interval between the neighboring emission peaks is the detuningδof the bichromatic field.When the ratio between Rabi frequency intensity and the detuningδof the bichromatic field remains unchanged,the intensity of each emitted peak remains invariant.The spontaneously emitted peak can be annihilated in the band gap and enhanced near the band edge in the anisotropic photonic crystals.Meanwhile,we also observe the fluorescence quenching phenomenon in the spontaneous emission spectra.The research in this paper provides the theoretical guidance for the control of atomic spontaneous emission.

Fluorescence Emission Spectrum of Elodea Leaves Exposed to Nanoparticles

The intensive use of engineered nanoparticles (NPs) in industrial, agricultural and household applications will very likely lead to the release of such materials into the environment, especially water ecosystems. Water plants are an integral part of ecosystems;hence their interaction with NPs is inevitable. It is important to understand the consequences of this interaction and assess its potential effects. There are different types of approaches for investigating the toxic effects of NPs on plants. Chlorophyll fluorescence (ChlF) is one of interesting biophysical methods for testing the effects NPs on plants in vivo. ChlF is a suitable technique and a very powerful tool for the in vivo studying of photochemical and non-photochemical processes within thylakoid membranes, chloroplasts, plant tissues, and whole plants. The present work reports the in vivo observation of chlorophyll a fluorescence quenching induced by the iron (Fe3O4, Fe2O3) and aluminum oxide (Al2O3) nanoparticles. Excitation and emission spectra of intact leaves of Elodea were acquired by fluorescence spectrophotometer (Cary Eclipse) at room temperature. It was shown that the intensity of the ChlF decreased in the solution of Fe3O4 and Al2O3 nanoparticles on the light. Fe2O3 affected slightly and the toxicity of nanoparticles depended on dose and exposure period. It was clear from these experiments that the given nanoparticles penetrated into the cell and might decrease the chlorophyll content of leaves.

Blue-Red Tuning Emission of ZnO: Europium Quantum Dots with Different Excitation Wavelengths

Optoelectronic applications require the development of new fluorescent and efficient luminescent materials, free of toxicity, low in cost, and easy to produce. In this way the synthesis of zinc-oxide (ZnO) quantum dots (QDs) has recently received special attention due to their good optical, electrical and chemical properties with low production costs and blue light emission. In this work ZnO QDs were successfully doped with europium in order to obtain a tunable emission luminescence from blue emission of ZnO to red emission of europium as a function of wavelength excitation. Results show an efficient blue to red tuning when the excitation wavelength was changed from 317 nm to 395 nm, respectively. This opens the possibility of having new optical devices to produce different color emission using the same material.

Research into Excited Long Lived 0.6-6.0 keV Energy Levels in the Cathode Solid Medium of Glow Discharge by X-Ray Emission Registration

X-ray emission from metal cathodes in glow discharge （current is up to 300 mA, voltage is 1,500-4,300 V） experiments in the spectral range from 700 eV to 6 keV has been observed. The effect has been seen with a variety of different metal cathodes （including AI, Sc, Ti, V, Ni, Nb, Zr, Mo, Pd, Ta, W, and Pt）, as well as with different gasses （including D2, H2, Kr, Ar, and Xe） at low pressure （3-10 Torr）. We present results from a variety of diagnostics, including： pinhole camera imaging; thermo luminescent detector measurements; time-resolved scintillator measurements; and a curved mica spectrometer to register X-ray spectra. Both diffuse and collimated X-ray emission have been observed.. Diffuse emission occurs in bursts of X-rays; with up to 10^5 bursts per second, with up to 10^6 photons per burst during the discharge. Collimated X-ray emission appears in the form of beamlets directed normal to the cathodes surface with a very small angular divergence; with up to 104 bursts per second, and up to 1013 photons overall up to 20 h after discharge switch off. Based on these experimental results we propose a phenomenological model of processes.

Effects of Doubled_CO_2 Concentration on Ultrastructure, Supramolecular Architecture and Spectral Characteristics of Chloroplasts from Wheat

Wheat ( Triticum aestivum L.) plants were grown under ambient and doubled_CO 2(plus 350 μL/L) concentration in cylindrical open_top chamber to examine their effects on the ultrastructure, supramolecular architecture, absorption spectrum and low temperature (77 K) fluorescence emission spectrum of the chloroplasts from wheat leaves. The results were briefly summarized as follows: (1) The wheat leaves possessed normally developed chloroplasts with intact grana and stroma thylakoid membranes; The grana intertwined with stroma thylakoid membranes and increased slightly in stacking degree and the width of granum, in spite of more accumulated starch grains within the chloroplasts than those in control; (2) The particle density in the stacked region of the endoplasmic fracture face (EFs) and protoplasmic fracture face (PFs) and in the unstacked region the endoplasmic fracture face (EFu) and the protoplasmic fracture face (PFu) was significantly higher than that of control. Furthermore, in some cases many more particles on EFs faces of thylakoid membranes appeared as a paracrystalline particle array; (3) The variations in the structure of chloroplasts were consistent with the absorption spectra and the low temperature (77 K) fluorescence emission spectra of the chloroplasts developed under the doubled_CO 2 concentration. Results indicate that the capability of light energy absorption of chloroplasts and regulative capability of excitation energy distribution between PSⅡ and PSⅠ were raised by doubled_CO 2 concentration. This is very favorable for final productivity of wheat.

￣(151)Eu-MOSSBAUER SPECTRA AND XPS INVESTIGATION OF BaFBr:Eu PHOSPHOR

Eu Mossbauer spectra of BaFBr:Eu phosphor are reported for the first time.The results show that f(Eu(2+) )<f(Eu(3+)) or <x2>Eu(2+)><x2>Eu(3+),which indicates that the attraction between phonons and Eu(2+) is stronger than that between phonons and Eu(3+),this may cause a faster increase of f(Eu=(2+)vs f(Eu(3+)) when temperature decreases as observed in the experiments.It is also found from Mossbauer investigation that when temperature decreases,the relative content of Eu(2+) decreases, while that of Eu(3+) increases.The temperature dependent Mossbauer spectra provide evidence for electron exchange or hopping between Eu(2+) or Eu(3+) sites in BaFBr lattice. The Mossbauer results are discussed and compared with the results of XPS and Photoluminescence studies.