Multiphoton Ionization Spectrum of Nitrogen Oxide by D2∑←X2∏

The resonance-enhanced multiphoton ionization (REMPI) spectrum of NO has been obtained. The spectral lines can be attributed to NO D2∑←X2∏ transitions. NO molecules are ionized via the resonant intermediate D2∑ states and by (3+2) REMPI process.     

Impact of fine particles on the direct current electric field of the conductor due to corona discharge

Corona-generated ionized field is an essential electromagnetic parameter of high voltage direct current transmission lines. In order to investigate the impact of atmospheric fine particles on the DC ionized field, distributions of the ground-level ionized field and ion current density were measured under various air contamination extents in a wire-to-ground platform. The fine particles were generated from burning incense. Measurement results show that the magnitude of ground-level ionized field may increase approximately by 20% when particles in the order of 10² μg m⁻³ exist in air. Restriction effect on the ionized field by using grounded shielding lines was also examined.     

Investigation of exciton complexes in 6H-SiC by isotope substitution

Unintentionally doped single crystals of 6H|SiC generally exhibit at low temperature a luminescence spectrum consisting of three zero phonon lines and a series of strong phonon replicas at lower energies including lines due to a localized vibrational mode. The fact that this localized mode shows no change for crystals doped with ¹⁵N, ¹⁰B or ¹⁸O is regarded as strong evidence that this spectrum is not due to the recombination of excitons at ionized nitrogen donors as has been reported by other authors, nor to recombination at centres involving the aforementioned impurities.     

NO分子共振增强的多光子离化机制

用皮秒Nd：YAG激光器泵浦光学参量发生／放大器做激发源,获得了420～480nm波长范围内NO分子的多光子离化谱。通过对谱线的归属,分析确定了NO分子的离化为以A^2∑为中间共振态的(2 2)共振增强的多光子离化过程。以速率方程为基础,利用激光脉宽较窄(35ps)的条件,推导出离化信号随激光强度呈近四次方变化关系,与实验测量结果相符,这可为用共振增强多光子离化(REMPI)光谱技术探测污染物NO分子提供实验参考。     

Harmonic measure and winding of conformally invariant curves

The exact joint multifractal distribution for the scaling and winding of the electrostatic potential lines near any conformally invariant scaling curve is derived in two dimensions. Its spectrum f(alpha,lambda) gives the Hausdorff dimension of the points where the potential scales with distance r as H approximately r(alpha) while the curve logarithmically spirals with a rotation angle phi=lambdalnr. It obeys the scaling law f(alpha,lambda)=(1+lambda(2))f(alpha)-blambda(2) with alpha=alpha/(1+lambda(2)) and b=(25-c)/12, and where f(alpha) identical with f(alpha,0) is the pure harmonic measure spectrum, and c the conformal central charge. The results apply to O(N) and Potts models, as well as to stochastic L?wner evolution.     

基于多光子电离的乙醇团簇飞行时间质谱研究

YAG脉冲激光倍频输出的532 nm和355 nm激光对脉冲分子束超声膨胀产生的中性乙醇团簇进行了电离,通过飞行时间质谱测量发现355 nm激光可对其实现3光子共振电离,观测到质子化的团簇离子序列(CH3CH2OH)nH+和 (CH3CH2OH)n (H2O)H+,其中(CH3CH2OH)3H+具有幻数结构.结合密度泛函理论中的B3LYP杂化方法加6-31G++基组水平上的计算,对质子化乙醇离子的结构及稳定性进行了推测,并讨论了乙醇团簇电离后的质子转移反应生成质子化团簇的机理.而对于另一个水合质子化团簇序列(CH3CH2OH)n(H2O)H+,由于溶剂化的影响只在较大尺寸时才出现.     

Experimental transition probabilities in the Ar III and Ar IV UV spectra

We present transition probabilities (Einstein's A values) for 38 Ar III (doubly ionized argon) and 14 Ar IV (triply ionized argon) spectral lines from the wavelength interval 240–308 nm. Considered spectral lines are recorded in laboratory pulsed discharge. The relative line intensity ratio procedure has been applied in evaluation of transition probabilities. As a reference for transition probability evaluation we have chosen A value of 241.884 nm spectral line in Ar III spectrum and A value of 280.947 nm in Ar IV spectrum, both obtained theoretically. Careful analysis of experimental and existing theoretical data is conducted in order to deduce uncertainties. Presented Ar III and Ar IV A values are for the first time obtained relying on experimental data.     

TiVI真空紫外光谱

用1m法向入射光谱仪观察三电极真空火花发射的Ti五次离化光谱。在24～200nm波段内观察到157条TiVI的新谱线。根据新归属的TiVI谱线定出11个新能级,并对5个有疑问的能级值作了修正。     

On the Cd III spectrum in a pulsed helium discharge

On the basis of the spectral line intensity relaxation during the plasma decay, fifty six spectral lines between 219 nm and 330 nm in the cadmium (Cd) spectrum were identified as Cd III (doubly ionized) or Cd IV (triply ionized) lines. The measured Stark widths of twelve, the most intense spectral lines around 315±15 nm with well defined profiles, are presented. Investigated spectral lines originate from the high lying energy levels, not classified up to now. A linear low-pressure pulsed arc was used as an optically thin plasma source. A pulsed discharge was produced in a pyrex discharge tube. Helium was chosen as the carrier gas. The cadmium atoms were sputtered from the thin cadmium cylindrical plates located in the homogeneous axial part of the discharge tube. The helium plasma was operated at electron temperatures up to 19 000 K and 1.1 × 10²³ m^-3 electron density. The stepwise ionization processes via the high lying singly ionized (Cd II) energy levels, populated well due to the Penning and charge exchange effects, provide high density of the Cd III (and Cd IV) ions in our helium plasma. The temporal evolutions of the spectral line intensities were monitored using a spectrograph and an ICCD camera as a highly sensitive detection system.     

高离化态镍的光谱

在中国原子能研究院串列加速器上利用束箔技术研究了120-400 ? 镍的高离化态镍光谱.验Ni XIII to XX研究中得到的谱线大多数属于Ni XIII 到 XX的跃迁,18条谱线是测量到的.     

NO2分子589.3～594.0 nm荧光激发谱转动分析

本文报道了实验测定的ＮＯ２分子在５８９．３￣５９４．０ｎｍ范围的高分辨荧光激发谱,对其中１１个振动带较完整的转动分析表明,荧光谱线主要来自＾２Ｂ２（Ｋ＝０）→＾２Ａ１（Ｋ＝０）的平行跃迁,得到了各带光谱数,并对光谱结构复杂性进行了讨论。     

New Classified Lines and Energy Levels in the Ne IV Spectrum

The spectrum of triply ionized neon, Ne IV, emitted by pulsed light sources has been studied. Ninety‐three new classified lines are reported, and the wavelengths of 99 previously observed and classified lines are improved. Using these data, it was also possible to determine 7 new energy levels and to adjust the value for 32 previously reported levels.     

Tabletop nucleosynthesis driven by cluster Coulomb explosion

Coulomb explosion of completely ionized (CH4)n, (NH3)n, and (H2O)n clusters will drive tabletop nuclear reactions of protons with 12C6+, 14N7+, and 16O8+ nuclei, extending the realm of nuclear reactions driven by ultraintense laser-heterocluster interaction. The realization for nucleosynthesis in exploding cluster beams requires complete electron stripping from the clusters (at laser intensities I(M) > or = 10(19) W cm(-2)), the utilization of nanodroplets of radius 300-700 A for vertical ionization, and the attainment of the highest energies for the nuclei (i.e., approximately 30 MeV for heavy nuclei and approximately 3 MeV for protons).     

Photoluminescence spectra of intracenter 4f transitions of rare-earth metal dopants in crystalline ZnO films

The influence of annealing in the medium of an ionized nitrogen, additionally introduced impurities, and regimes of post-growth annealing on photoluminescence spectra of intracenter 4f transitions of rare-earth metal dopants (Ce, Eu, Sm, Er, Tm, Yb) in crystalline ZnO films has been investigated. The films have been prepared using molecular-beam epitaxial growth and magnetron sputtering. According to the X-ray diffraction analysis, the films have a single-crystal structure. It has been shown that the annealing in the medium of an ionized nitrogen, regardless of the method used for producing the ZnO films, leads to significant changes in the photoluminescence spectrum, i.e., to a decrease in the emission intensity and a shift in the position of the emission maximum toward the long-wavelength range of the spectrum. The nitrogen concentration has been determined by the nuclear reaction method. It has been revealed that the spectra contain intense emission lines due to the intracenter 4f transitions of rare-earth elements (Sm, Er, Tm, Yb) in the crystalline ZnO films prepared by magnetron sputtering, and the intensity of the emission lines increases upon introduction of codopants, namely, Ce and Er.     

Investigation of trace p-dichlorobenzene using laser mass spectrometry

The time-of-flight mass spectrum (TOFMS) relative to the resonant two-photon ionization of gas phase pdichlorobcnzene was obtained in the wavelength range of 240 - 250 nm by a home-made system. A special design was made to reduce the effect of memory on the inner wall of the sample inlet system suitable for the investigation of semi-volatile organic compound. In this wavelength range, p-dichlorobenzene molecules firstly absorbed one photon to be excited from the ground state 1A9(So) to the first excited state 1B2u (S1), then absorbcd another photon to be ionized. The relationship between the signal intensity of p-dichlorobenzene molccular ion C6H435Cl at 248-nm wavelength and the laser power was given. The 1.52 power index of C6H435Cl2 was a typical identification of the 3/2 power law. The relationship between the ion signal intensity of C6H435Cl and the sample concentration was close to a linear one in the ppm(V/V) range, which led to a detection limit of 125 ppb(V/V) for p-dichlorobenzene.     

A theoretical and experimental investigation of long-pulse,electron-beam-produced rare gas plasmas

Visible emission spectroscopy (380-650 nm) has been performed on intense, electron beam (1 kA, 300 ns, 300 kV) produced Ar, Kr, and Xe plasmas at pressures ranging from 10 to 750 torr. Singly ionized and neutral lines dominated the spectra in all cases except argon, where only singly ionized lines occurred. The temperature of the plasma as determined by comparing line intensities was between 1 and 2 eV. A computer model for chemical kinetics of the electron-beam-produced plasmas in Ar, Kr, and Xe was formulated. The model predicts time, pressure, and temperature trends of the ions, neutrals, and electrons, which agree with trends found experimentally     

甲烷电离特性的等离子体发射光谱法研究

应用等离子体发射光谱法,用CCD(charge coupled device)光栅光谱仪记录并标识了脉冲电晕甲烷等离子体370～1 100 nm的发射光谱,确定了常温常压下高纯甲烷(99.99%)经100 kV, 100 Hz脉冲高压电离后的产物为H,C+,CH,C,C₂,C₃, C₄,C₅和烃等。通过分析实验检测到的甲烷等离子体发射光谱,给出了甲烷经脉冲高压电离形成电晕等离子体的机理和自由基CH_n(n=3,2,1)、碳、烃等产物的电离途径。结果显示甲烷分子经高能电子非弹性碰撞后脱氢程度很高,大量氢原子及其离子和甲烷自由基在进一步被高能电子作用下合成了烯烃、炔烃、烷烃和高聚碳化物。实验所获得的脉冲甲烷等离子体发射光谱及其机理分析可为甲烷及其转化研究提供相关依据。     

Spectroscopic constraints on the surface magnetic field of the accreting neutron star EXO 0748-676

Gravitationally redshifted absorption lines of Fe XXVI, Fe XXV, and O VIII were inferred recently in the x-ray spectrum of the bursting neutron star EXO 0748-676. We place an upper limit on the stellar magnetic field based on the iron lines. The oxygen absorption feature shows a multiple component profile that is consistent with Zeeman splitting in a magnetic field of approximately (1-2) x 10(9) G and for which the corresponding Zeeman components of the iron lines are expected to be blended together. In other systems, a field strength > or approximately 5 x 10(10) G could induce a blueshift of the line centroids that would counteract gravitational redshift and complicate the derivation of constraints on the equation of state of the neutron star.     

Infrared absorption spectrum of singly ionized magnesium donors in silicon

The infrared absorption spectrum of singly ionized magnesium donor impurities in silicon has been measured. Due to better sample preparation and higher resolution of the instrument, the absorption spectrum obtained is much better than previous reports. Some new lines have been observed and identified. Besides the 2p_± line, the 3p_± line has also been observed for the first time to be a doublet indicating that the excited state np_± splits into two states due to chemical splitting.     

LaseRitz: Far-Infrared Laser Line Assignment and Prediction by the Ritz Combination Principle, with Application to Methanol and Hydrazine

A "LaseRitz" program is described for the systematic assignment and prediction of far-infrared laser (FIRL) transitions for a given molecule, such as methanol or hydrazine, which can be generated by optical pumping with known laser lines. The input data set for the program consists of identified molecular energy levels in ground and excited vibrational states, as compiled by our Ritz assignment program from the analysis of infrared (IR) bands and the FIR ground state spectrum. The program scans the data set for appropriate IR matches with an input list of laser pump lines for CO(2), N(2)O, etc., and generates an output table of all possible FIRL lines consistent with the molecular selection rules and lying within a prescribed wavenumber range. Initial tests on CH(3)OH have led to three likely new FIRL assignments; for N(2)H(4), assignments have been found for 14 new FIRL transition systems and verified for five others. Lists have been produced (deposited as supplementary data with the JMS archive reached at www.idealibrary.com or available on request from the authors) of CH(3)OH and N(2)H(4) FIRL lines potentially accessible by optical pumping with regular, sequence-band, hot-band, and isotopic CO(2) lines, plus N(2)O lines for N(2)H(4). The systematic approach with the LaseRitz program is more global and rigorous than earlier line-by-line studies, permitting calculation of all FIRL wavenumbers to spectroscopic accuracy. Copyright 2000 Academic Press.