Wavelengths Of Lines Research Articles

THEORETICAL WAVELENGTHS OF Fe XVI L-SHELL TRANSITIONS AND COMPARISON WITH LABORATORY MEASUREMENTS ANDCHANDRAOBSERVATIONS OF CAPELLA

We have used the relativistic multi-reference Moller-Plesset perturbation theory to calculate the energy levels of Fe XVI, including those of the autoionizing levels with a hole state in the L shell. Comparison of the resulting L-shell transition wavelengths with those from recent laboratory measurements shows remarkable agreement, i.e., agreement within the experimental uncertainties. Our calculation allows us to predict the wavelength of the second strongest 2p-3d Fe XVI line, which has not yet been directly observed in the laboratory, to be 15.266 A. This wavelength is within 0.0042 A of the strong Fe XVII line commonly labeled 3D. Relying on the high accuracy of our calculations, we have reassigned two previously identified lines and predict a different location than previously thought for the strongest Fe XVI magnetic quadrupole transition. Inspection of the spectra of Capella recorded with the transmission grating spectrometers on the Chandra X-ray Observatory yields features corresponding to the predicted location of the innershell excited Fe XVI lines. These features have not been identified before. Our analysis shows that these features are most likely from Fe XVI.

Revised and extended analysis of doubly ionized selenium: Se III

The spectrum of selenium was recorded on a 3 m normal incidence vacuum spectrograph of the Antigonish laboratory (Canada) in the wavelength region 300–2080 Å using a triggered spark source. The theoretical structure of doubly ionized selenium (Se III) was predicted by Cowan's multi-configuration interaction code. The ground configuration of Se III is 4s24p2 and the excited configurations are of the type 4s24pnd (n⩾4), 4s24pns (n⩾5) and the inner shell excitation gives rise to the 4s4p3 configuration. The 4s24p2−[4s4p3+4s24p (4d+5d+6d+7d+5s+6s+7s+8s)] transition array has been analyzed. Several earlier reported levels have been revised and four new configurations have been added. All the levels of these configurations have been established. More than 180 spectral lines have been identified in this spectrum. A total of 75 energy levels belonging to the above-mentioned configurations have been established. Least-squares fitted parametric and Hartree–Fock calculations were used to interpret the observed spectrum. Excellent agreement with theoretical calculations was noticed. The standard deviation of least-squares fit is only 110 cm−1. The ionization potential of Se III was found to be 255 650±150 cm−1 (31.696±0.018 eV). The accuracy of our wavelengths for sharp lines is better than ±0.005 Å.

Remote laser‐induced breakdown spectroscopy (LIBS) for lunar exploration

Laser‐induced breakdown spectroscopy (LIBS) is an active analytical technique that makes use of a laser pulse to analyze materials of interest at a distance by creating a plasma, which emits photons at characteristic emission line wavelengths. We validate the technique for planetary exploration under vacuum conditions. We review the capability and advantages of the LIBS technique for lunar regolith analysis at 1.5 m distance from a lunar rover, and we characterize its potential for the detection of resources for future exploration, such as the determination of regolith water content. The limits of detection determined for the major elements (typically <1 wt %) help to determine regolith parent material such as feldspathic highland rocks, rocks from the ancient magmatic high magnesian suite (Mg‐suite), Fe‐rich mare basalts or potassium, rare earth element, and phosphorus‐rich (KREEP‐rich) samples. Compositional parameters commonly used to classify lunar regoliths such as TiO2, Al2O3, and K2O abundances are readily determined by LIBS. Certain elements support regolith analysis: For example, Ba and Zr can be used to confirm KREEP‐like composition, while quantifying the Ni and Co content can be used to infer the amount of meteoritic material. Finally, it is shown that the ice content of lunar soil produces strong H emissions with the LIBS techniques at the 25 wt % H2O level, while measurements on altered basalts give a limit of detection of about 1 wt % for H2O content. This demonstrates that the 5.6 wt % water content detected by the recent LCROSS experiment should be easily detectable and quantifiable by LIBS analysis.

Collisional Excitation of SO2in Cold Molecular Clouds

Using recently calculated collisional rates for SO2 with ortho and para molecular hydrogen, we have calculated the expected emission of the centimeter wavelength lines of SO2 for the physical conditions previling in dark molecular clouds. We have found that the transition connecting the metastable 202 level with the 111 one will be in absorption against the cosmic background for a large range of densities. The 404 -313 line is found to be masering for densities below a few 104 cm−3 . We have observed the 111 -202 transition with the GBT telescope towards some dark clouds. The line is observed, as expected, in absorption and provides an abundance of SO2 in these objects of a few 10−10 . The potential use of millimeter lines of SO2 as tracers of the physical conditions of dark clouds is discussed.

Transmission Line Characteristics Based on Metamaterials Substrate

The novel transmission line based on metamaterials substrate was studied theoretically. The characteristic impedance and transmission wavelength of such transmission line are analytically calculated in framework of classical transmission-line theory. Moreover, the characteristic of similar micro-strip line were also studied with FEM simulation. Results showed that using metamaterials as a substrate, the characteristic impedance would be greatly increased, providing a new method to reduce the loss in the RF circuit. The transmission wavelength would be effectively extended at the same frequency. That was the electromagnetic radiation would greatly reduce in such RF circuit. Once the transmission wavelength was much larger than the size of the circuit board, the circuit theory could be adopted in RF design. Which would greatly reduce the difficulty of RF design.

The new SI based on fundamental constants

The papers in this Discussion Meeting Issue of Philosophical Transactions A are based on the presentations given at a Discussion Meeting held at the Royal Society in London on 24 and 25 January 2011 entitled ‘The new SI: units of measurement based on fundamental constants’. The meeting was

Multiconfiguration Dirac-Fock calculations on multi-valence-electron systems: Benchmarks on Ga-like ions

High-accuracy calculations of term energies and wavelengths of resonance lines in Ga-like ions have been performed as benchmarks in the request for accurate treatments of relativity, electron correction, and QED effects in multi-valence-electron systems. The calculated energy levels are in excellent agreement with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in good agreement with other theoretical and experimental values for low- to medium-$Z$ ions. On the basis of our calculations, some theoretical wavelengths for Ga-like Rb vii to Mo xii are also given. For higher-$Z$ ions, computed wavelengths are compared well with the experimental results [E. Tr\abert, J. Clementson, P. Beiersdorfer, J. A. Santana, and Y. Ishikawa, Phys. Rev. A 82, 062519 (2010), I. N Dragani\ifmmode \acute{c}\else \'{c}\fi{} et al., J. Phys. B 44, 025001 (2011)].

Optical Fiber CO Concentration Measurement Prism of the Gas Chamber Variable Optical Path Automatic Adjustment System Research

According to the absorption spectrum, combined with CO distribution feedback type laser diode (DFB-LD) light source, we selected R a center for 1567.3 nm as the wavelength of the absorption spectrum line. Comprehensively using of prism of gas chamber and harmonic detection technology, we constructed the optical fiber CO concentration measurement system. Through the stepping motor regulation height, it changes indoor prism gas effective absorption process, adjusts the light sensitivity system.

CXO CDFS J033260.0-274748: A quasar with unusual spectra possibly blueshifted?1This paper is being published without benefit of authors’ corrections.

CXO CDFS J033260.0-274748 is a quasi-stellar object (QSO) and identification of several emission lines observed in its optical spectrum has led to the determination of its redshift as 2.579. On the other hand, the Chandra ACIS-I spectrum has detected a strong absorption feature at the observed wavelength around 6.3 keV that cannot be identified under normal physical conditions. The authors have invoked an unusually large outflow bulk velocity of 0.7c–0.8c to explain the feature. However, such extraordinarily high bulk velocities are unprecedented in the extragalactic literature. We show here that the optical emission lines and the X-ray absorption feature can be identified with search lines of longer wavelengths that have been blueshifted and do not need any unusual physical conditions to be invoked. The blueshifted spectra are explained as being due to the net motion of the QSO along with the absorbing cloud towards the observer. Two scenarios are proposed, namely, the ejection mechanism and the multiverse.

Generation of a twin beam at the cesium line and telecom wavelength by cavity phase matching

Cavity phase matching has been recently demonstrated as a phase-matching method for efficient nonlinear frequency conversion in a microcavity. Here we extend it to the Type I configuration using a sub-coherent-length optical parametric oscillator consisting of an MgO-doped lithium niobate crystal sheet. It generates a tunable single-longitudinal-mode twin beam, which covers the cesium D2 line of 852.1 nm and the extended band of optical communication. This microcavity is capable of peak output power of 58 kW with a maximum conversion efficiency of 18.5%. Broad applications in the areas of light-atom interaction, spectroscopy, optical telecommunication, and quantum optics can be expected.

Two-level lasers operating on the transitions to the ground state

We analyze in detail a model of two-level lasers with a thermal production of population inversion proposed by V. A. Gerasimov et al. (Phys. Rev. Lett., 2006, 96, 123902). We show that it is possible to obtain nine new laser lines on the transitions to the ground state in atoms of rare-earth metals (REMs) with an incomplete 4f shell (Pr, Nd, Sm, Eu, and Tb–Tm). The laser line wavelengths are from the UV (Eu) to the middle IR (Tb and Er) regions of the spectrum. Based on the estimates of the specific laser energy parameters (power, power density, and efficiency), we conclude that only Sm, Eu, and Tm (among the REMs under study) are suited for the experimental prototypes of these lasers. The estimated maximum efficiency and specific power density of continuous lasing can reach the values of >40% and ~107÷109 W/cm2, respectively.

Photocatalytic activity of TiO2 sensitized by CdS quantum dots under visible-light irradiation

In this paper, CdS quantum dots sensitized TiO2 composite powders (QD-CdS/TiO2) were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern (XRD) shows the crystal structures of CdS and TiO2 are cubic phase and anatase phase separately in QD-CdS/TiO2 powder samples; the crystal size of CdS in QD-CdS/TiO2 is about 3–7 nm, while TiO2 crystal size is about 20 nm. With increasing CdS content in QD-CdS/TiO2 composite, the UV-Vis absorption spectrum shifted to the longer wavelength lines, exhibiting obvious quantum size effect. The fluorescence intensity of QD-CdS/TiO2 irradiated by blue light is weaker than that of pure CdS. When the molar ratio of CdS and TiO2 is about 1:2, the QD-CdS/TiO2 powder has the best catalytic properties under visible-light irradiation, and the degradation rate of rhodamine B (RhB) is up to 92.2% within 60 min.

NARROWBAND IMAGING OF ESCAPING LYMAN-CONTINUUM EMISSION IN THE SSA22 FIELD,

We present the results of an ultradeep, narrowband imaging survey for Lyman-continuum (LyC) emission at z~3 in the SSA22a field. We employ a custom narrowband filter centered at 3640A (NB3640), which probes the LyC region for galaxies at z>3.06. We also analyze new and archival NB4980 imaging tuned to the wavelength of the Lya emission line at z=3.09, and archival broadband B, V, and R images of the non-ionizing UV continuum. Our NB3640 images contain 26 z>3.06 Lyman Break Galaxies (LBGs) as well as a set of 130 Lya emitters (LAEs), identified by their excess NB4980 flux relative to the BV continuum. Six LBGs and 28 LAEs are detected in the NB3640 image. LBGs appear to span a range of NB3640-R colors, while LAEs appear bimodal in their NB3640-R properties. We estimate average UV to LyC flux density ratios, corrected for foreground contamination and intergalactic medium absorption, finding <F_{UV}/F_{LyC}>^{LBG} = 11.3^{+10.3}_{-5.4}, which implies a LBG LyC escape fraction f_{esc}^{LyC} ~ 0.1, and <F_{UV}/F_{LyC}>^{LAE} = 2.2^{+0.9}_{-0.6}. The strikingly blue LAE flux density ratios defy interpretation in terms of standard stellar population models. Assuming <F_{UV}/F_{LyC}>^{LBG} applies down to L=0.1L*, we estimate a galaxy contribution to the intergalactic hydrogen ionization rate that is consistent with independent estimates based on the Lya forest opacity at z~3. If we assume that <F_{UV}/F_{LyC}>^{LAE} holds at the faintest luminosities, the galaxy contribution significantly exceeds that inferred from the Lya forest. Further follow-up study of these faint LAEs is crucial, given the potentially important contribution similar objects make to the process of reionization. (Abridged)

Collisional excitation of sulfur dioxide in cold molecular clouds

We present collisional rate coefficients for SO2 with ortho and para molecular hydrogen for the physical conditions prevailing in dark molecular clouds. Rate coefficients for thefirst 31 rotational levels of this species (energies up to 55 K) and for temperatures between 5 and 30 K are provided. We have found that these rate coefficients are about ten times more than those previously computed for SO2 with helium. We calculated the expected emission of the centimeter wavelength lines of SO2. We find that the transition connecting the metastable 202 level with the 111 one is in absorption against the cosmic background for a wide range of densities. The 404−313 line is found to be inverted for densities below a few 10 4 cm −3 . We observed the 111−202 transition with the 100 m Green Bank Telescope towards some dark clouds. The line is observed, as expected, in absorption and provides an abundance of SO2 in these objects of af ew 10 −10 . The potential use of millimeter lines of SO2 as tracers of the physical conditions of dark clouds is discussed.

Análise dos transientes de ondas de tensão em ambos os extremos de uma linha quarto de onda e analogia com o fenômeno de reflexão e transmissão de ondas eletromagnéticas

Os valores estacionários da amplitude de uma onda de tensão em ambos os extremos de uma linha quarto de onda foram determinados através de uma análise de transiente, para um frente de onda incidente de tensão senoidal. Foram levadas em conta as múltiplas reflexões e transmissões parciais da onda incidente, junto com o acúmulo de fase devido à propagação. Foram também derivadas expressões genéricas para o caso mais geral de uma linha de comprimento qualquer. Foi mostrado que existe uma total analogia entre o estudo apresentado neste trabalho e a reflexão e transmissão de ondas eletromagnéticas na interface entre dois médios dielétricos diferentes.

Recent progress in spectroscopy of tungsten1This review is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

This contribution reviews experimental and theoretical work on spectroscopy of tungsten published since the last critical compilation of the energy levels and spectral lines of highly ionized tungsten (Kramida and Shirai. At. Data Nucl. Data Tables, 95, 305 (2009)). Since then, 18 new experimental studies were published, which resulted in new identifications and (or) significantly improved wavelengths of spectral lines and energy levels of Li-like through As-like and Pm-like tungsten. A few tens of theoretical studies of tungsten spectra were published since 2008. A number of them report on high-precision calculations of energy levels, transition wavelengths, and radiative rates for tungsten spectra, such as neutral tungsten, Yb-like, Rh-like through Rb-like, Ag-like, Ga-like, Zn-like, Ni-like, Ca-like, Al-like, Mg-like, Na-like, Ne-like, B-like, Be-like, and Li-like. These developments are reviewed. Based on new experimental data, systematic errors are removed from some of the earlier measurements. Some new data are obtained by analyzing publications of other authors. Based on new published theoretical data, some old experimental results were confirmed and assessed. Revised and extended tables of energy levels and spectral lines of highly ionized tungsten are presented.

Compact and Tunable Slot-Loop Antenna

A compact and tunable slot-loop antenna is studied in this communication. By periodically loading the slot line with varactor diodes, the slow-wave loop is capable of operating at frequencies from 2.34 GHz to 4 GHz with the measured input reflection coefficient better than -7.5 dB while occupying a small footprint of 0.072 λg × 0.072 λg (8.1 mm × 8.1 mm), where λg is the guided wavelength of a slot line at 2.34 GHz. The slot-loop in the ground plane is excited by a simple microstrip line, which enables the impedance matching from 3.2 GHz to 4 GHz for VSWR ≤ 2. A LC low-pass circuit is configured into the bias network to isolate the RF signal from the DC power path and consistent radiation patterns are experimentally obtained across the entire tunable frequencies of interest. The slot loop combined with the feed line and the bias circuitry is only 40 mm × 38.97 mm. Experimental results validate the feasibility of the presented antenna and agree well with simulation data.

The Extreme Low‐Frequency Raman Spectrum of Liquid Water

Not merely sloshing around: The chemical and physical properties of water are very important. In contrast to its simplistic chemical formula, water possesses a complex dynamic behaviour (see picture). The bend, torsion, symmetric and asymmetric stretch modes of liquid water, close to the wavelength of the laser line have been predicted. Here, the low-frequency Raman spectrum of liquid water is presented confirming the presence of all four modes in the restricted translational region (35–300 cm−1).

BROAD COMPONENTS IN OPTICAL EMISSION LINES FROM THE ULTRA-LUMINOUS X-RAY SOURCE NGC 5408 X-1

High-resolution optical spectra of the ultraluminous X-ray source NGC 5408 X-1 show a broad component with a width of ~750 km/s in the HeII and Hbeta lines in addition to the narrow component observed in these lines and [O III]. Reanalysis of moderate-resolution spectra shows a similar broad component in the HeII line. The broad component likely originates in the ULX system itself, probably in the accretion disk. The central wavelength of the broad HeII line is shifted by 252 \pm 47 km/s between the two observations. If this shift represents motion of the compact object, then its mass is less than ~1800 M_sun.

Theoretical study of polarization atmosphere Michelsoninterferometer using multi-wavelength

The basic principle of measuring the upper atmosphere using the polarization atmosphere Michelson interferometer (PAMI) is briefly described. The relationships between the intensity and the visibility of the PAMI and the Delayed phase of the wave plate are presented. The visibility and the intensity of the PAMI are dependent on the wavelength of spectral line, showing that the 732nm line is inapplicable for measuring spectral line if the PAMI is designed specifically for the 630 nm line. The research provides a theoretical basis and practical guidance both for the theoretical study of polarization atmosphere Michelson interferometer and for the design and development of the new polarization atmosphere Michelson interferometer.