Lines Of Kr Research Articles

Measurements of the absolute intensities of spectral lines of Kr, Ar, and O ions in the wavelength range of 10 – 18 nm under pulsed laser excitation

We have measured the absolute intensities of the spectral lines of Kr, Ar, and O ions (CO2 gas), which are of interest for reflectometry, microscopy, and lithography in the wavelength range of 10 – 18 nm. We have used pulsed excitation by an Nd : YAG laser with an output wavelength λ = 1064 nm, a pulse energy of 0.8 J, a pulse duration of 5.2 ns and a pulse repetition rate of 10 Hz. The targets are formed during gas outflow through a pulsed supersonic conical nozzle for an inlet gas pressure of 3.5 bar. A spectrometer based on X-ray multilayer mirrors and its calibration procedure are described in detail. The absolute intensities of the spectral lines of Kr IX (λ = 11.5 nm; number of photons: N = 9.3 × 1012 photons pulse−1), Ar VIII (λ = 13.84 nm, N = 3 × 1012 photons pulse−1), and O VI (λ = 12.98 nm, N = 5.17 × 1012 photons pulse−1). The results are compared with the data obtained for Xe ions under the same experimental conditions at the same wavelengths.

Quasi-Molecular Optical Transitions near Resonance Lines of Kr and Xe Atoms in Helium

The emission and absorption spectra of Kr and Xe atoms near the 1,3P1–1S0 resonance lines in an atmosphere of helium atoms under equilibrium conditions have been theoretically investigated. Potential curves for excited states of Kr(4p55s) + He and Xe(5p56s) + He quasi-molecules are obtained with joint application of the effective Hamiltonian and pseudopotential methods. Experimental data are used for the ground state. Based on these potential curves, the spectral profiles of quasi-molecular emission and absorption for short-wavelength wings of the resonance lines are calculated within the quasi-static approximation. The results obtained for absorption are compared with the known experimental data.

The Influence of Molecular Gas on the Apokamp Discharge Formation

Emission spectra of apokamp discharge plasma jets in CO2, Ar, Kr, N2, and their mixtures have been studied. It has been shown that the emission spectra of the Kr–N2 mixture contain N2 and $$\rm{N_2^+}$$ bands, as well as Kr lines. The spectrum of the Ar–CO2 mixture is presented by bands of the Fox–Duffendack–Barker system and lines of the exited argon atom. In all gas media under study, the reduction of the molecular gas quantity leads to the transition from an apokampic discharge in the form of a diffusion jet developing from the current channel to a volume discharge with a strong transverse glowing. The experimental apparatus described in this work is proposed for use in laboratory investigations of spectral characteristics of transient luminous events observed in atmospheres of planets of the Solar System.

Stellar laboratories

For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. New of Kr IV - VII oscillator strengths for a large number of lines allow to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. We calculated Kr IV - VII oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines exhibited in high-resolution and high-S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289. We reanalyzed the effective temperature and surface gravity and determined Teff = 70 000 +/- 2000 K and log (g / cm/s**2) = 7.5 +/- 0.1. We newly identified ten Kr V lines and one Kr VI line in the spectrum of RE 0503-289. We measured a Kr abundance of -3.3 +/- 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km/s < vrad < +18 km/s. Reliable measurements and calculations of atomic data are a prerequisite for state-of-the-art NLTE stellar-atmosphere modeling. Observed Kr V - VII line profiles in the UV spectrum of the white dwarf RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths.

VII. New Kr IV - VII oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE 0503-289

For the spectral analysis of high-resolution and high signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. New Krivvii oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTEmodel-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods. We calculated Krivvii oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high SN ultraviolet (UV)observations of the hot white dwarf RE 0503.

Double K-shell ionization of Kr induced by swift Xe54+ ions

SynopsisKα satellite and hypersatellite lines of Kr induced by 52-, 94-, 146-, and 197-MeV/u Xe54+ ions were measured. Experimental values were compared with theoretical ones obtained within the independent electron model (IEM) employing single electron probabilities calculated with the semi-classical approach (SCA). This comparison suggests that first order perturbation approximation is consistent well with the experimental result at 197-MeV/u projectile collision while breaks down for the lower energies.

On the relative transition probabilities of rare gases in the 1si–2pj region

We have measured the relative transition probabilities of the 1si–2pj transitions in rare gases using hollow cathode lamps. The emission spectra of each rare gas were recorded as a function of discharge current. Two independent calibration modes for the spectrometer have been used to increase the reliability of our data. Uncertainty in the data have been measured and found to be within ~5%. The relative transition probabilities are reported for 30 lines of Ne I, 25 lines of Ar I, fourteen lines of Kr I, and eighteen lines of Xe I. The present results are in good agreement with the published data. The data can also be used to calibrate the relative detection efficiency of a spectrometer over a range of 400–1000nm.

Slow ions 84Kr15+, 17+ bombardment on GaAs

We have investigated surface morphology and visible light emission from slow ions Kr15+, 17+ colliding with GaAs (100). The surface disorder of GaAs films mainly depends on the charge state of incident ions. The two spectral lines of target atom Ga belong to transitions of GaⅠ 4p 2P1/2o5s 2S1/2 at 403.2 nm and 4p 2P3/2o5s 2S1/2 at 417.0 nm. Light emissions of target species depend on the energy of the incident ions deposited on the target surface atoms. During the neutralization process, the four spectral lines of Kr+ respectively can be attributed to the transitions of Kr Ⅱ 4d 4F7/25p 2D5/2o at 410.0 nm, 5s 2P3/25p 4S3/2o at 430.4 nm, 5p 4D3/2o4d 2D3/2 at 434.0 nm and Kr Ⅱ 4d 4D1/25p 2S1/2o at 486.0 nm. They are induced by cascade de-excitation after many electrons of the conductions band of the solid surface captured in highly excited states of the incident ion. Intensities of these six spectral lines from incident ions Kr17+ are obviously larger than Kr15+'s.

Visible Light Emission in Highly Charged Kr17+ Ions Colliding with an Al Surface

We report light emission during the bombardment of Kr17+ ions on an Al surface in the wavelength range 300–700 nm. The three spectral lines of the sputtered Al atoms belong to transitions of Al I 3p 2P°3/2−3d 2D5/2 at 309.26, Al I 3p 2P°1/2−4s 2S1/2 at 394.72 and Al I 3p2 P°3/2−4s 2S1/2 at 396.50 nm. During the neutralization process, the seven spectral lines of Kr I and Kr II from the incident ion of Kr17+ attribute to transitions of Kr I 5p 2[3/2]2−7d 2[1/2]°1 at 616.33, Kr II 5s 2D5/2−5p 2D°3/2 at 410.86, Kr II 5p 4P°5/2−6s 4P5/2 at 430.58, Kr II 4d 2D3/2−4f 2[3]°5/2 at 434.42, Kr II 4d 4D1/2−5p 2S°1/2 at 485.80, Kr II 4p 4S3/2−6s 4P°3/2 at 618.57 and Kr II 5p 4P°3/2−4d 2D5/2 at 656.41 nm. Light emissions of sputtered species depend on energy of the incident ions deposited on the target surface atoms. Light emissions of the neutralized projectiles are formed due to many electrons of the conduction band of the solid surface captured in excited states of the incident ion.

Sonoluminescence from OH(C2Σ+) and OH(A2Σ+) Radicals in Water: Evidence for Plasma Formation during Multibubble Cavitation

Bubble trouble: Multibubble sonoluminescence spectra in water under Kr and Xe present emission lines of OH(C2Σ+–A2Σ+). This band, never observed in flames, indicates plasma formation in the collapsing bubbles.

S‐Process Abundances in Planetary Nebulae

The s-process should occur in all but the lower mass progenitor stars of planetary nebulae, and this should be reflected in the chemical composition of the gas which is expelled to create the current planetary nebula shell. Weak forbidden emission lines are expected from several s-process elements in these shells, and have been searched for and in some cases detected in previous investigations. Here we extend these studies by combining very high signal-to-noise echelle spectra of a sample of PNe with a critical analysis of the identification of the emission lines of Z>30 ions. Emission lines of Br, Kr, Xe, Rb, Ba, and Pb are detected with a reasonable degree of certainty in at least some of the objects studied here, and we also tentatively identify lines from Te and I, each in one object. The strengths of these lines indicate enhancement of s-process elements in the central star progenitors, and we determine the abundances of Br, Kr, and Xe, elements for which atomic data relevant for abundance determination have recently become available. As representative elements of the ``light'' and ``heavy'' s-process peaks Kr and Xe exhibit similar enhancements over solar values, suggesting that PNe progenitors experience substantial neutron exposure.

Interaction between doubly-excited 4p4nℓn′ℓ′ resonances in KrI

Photoionization cross sections for the 4p4(3P)5s4P5/2,3/2,1/2 satellites and 4s → εℓ, 4p → εℓ main lines of Kr II were measured using the photon-induced fluorescence spectroscopy in the exciting-photon energy range between 27.80 eV and 29.44 eV with extremely narrow bandwidth (1.7 meV at 28.55 eV) of the monochromatized synchrotron radiation. The observed resonances were assigned to the 4p45s(4P1/2)np and 4p45s(2P3/2)np Rydberg series on the basis of the calculations including core relaxation and interaction between many resonances and many continua. The calculation shows that the resonance structure in the photoionization channels exists due to the 4p4(1D)5s2D5/26p3/2 and 4p4(1D)5s2D3/2 6p3/2,1/2 promoter states which strongly perturb the above Rydberg series.

A Spectrophotometric Survey ofK-Band Emission Lines in Planetary Nebulae

We present observations of 16 planetary nebulae (PNs) in the 2 μm (K band) spectral region, obtained with a long-slit near-infrared spectrometer at McDonald Observatory. In general, the strongest features in our spectra are recombination lines of H I, He I, and (in some cases) He II. Half the sample shows emission from vibrationally excited H2. Some of the observed PNs (e.g., M 1-13) display H2 line ratios characteristic of shocked, thermalized gas, while others (e.g., BD +30 3639) have ratios intermediate between pure radiative (UV) and shock excitation, consistent with either a combination of the mechanisms or UV illumination of dense material. Our spectra of J900 and M 1-13 confirm that published narrowband images trace the H2 emission, and we find that the H2 emission in SwSt 1 has a larger spatial extent than previously reported. In IC 5117, SwSt 1, and NGC 40 we detect the [Kr III] 2.199 μm line identified by Dinerstein in 2001, with strengths indicating that krypton is enriched relative to the solar abundance, most markedly so in NGC 40. We also detect several lines from the 3G term of [Fe III] in Vy 2-2, SwSt 1, and marginally in Cn 3-1. The [Kr III] and [Fe III] lines fall near in wavelength to H2 transitions, which are often used as diagnostics for UV excitation because they arise from higher vibrationally excited levels (v = 2, 3). For moderate spectral resolving power, R ≤ 600, these lines may be blended with, or even mistaken for, the corresponding H2 lines, leading to misinterpretation of the H2 emission. The strength of both the Kr and Fe nebular emission lines can be enhanced by special circumstances, Kr because of nucleosynthetic self-enrichment in the progenitor star and Fe due to inefficient initial dust condensation or partial destruction of the dust after formation, causing a larger fraction of the elemental iron to reside in the gas phase.

Reference wavelengths in the spectra of Fe, Ge, and Pt in the region near 1935 Å

Wavelengths of seven spectral lines of Fe I, Ge I, and Pt I between 1932 Å and 1938 Å have been measured with uncertainties of less than 1×10−4 Å (5 parts in 108) with Fourier-transform spectroscopy. These lines provide accurate standards for wavelength calibration of ArF excimer lasers operating at 193 nm. Previously reported wavelengths of Fe I, Cu II, and Ge I were evaluated for calibration of the absolute wavelength scale. Calibrations based on Fe I and Ge I were found to differ systematically by several parts in 108. A calibration based on Cu II was internally inconsistent at a level of 2 parts in 107 and was not used. Improved wavelengths for an additional 147 lines of Pt I and Pt II and 161 lines of Kr II in the region 1636 Å to 3151 Å are also reported.

VUV emission spectra from binary rare gas mixtures near the resonance lines of Xe I and Kr I

Emission spectra of Xe–X (X = He, Ne, Ar and Kr) and of Kr–Y (Y = He, Ne and Ar) mixtures with low concentrations of the heavier gases (0.1–1%) and moderate total pressures (50–200 hPa) have been recorded near each of the two resonance lines of Xe and Kr in DC glow capillary discharges. The recorded intense emissions have narrow spectral profiles with FWHM of about 0.1 nm. The profiles are very similar in shape to profiles of known high resolution absorption spectra recorded at comparable gas pressures. A tentative identification of the emission structures is given, which involves transitions in heteronuclear molecules and quasimolecules between weakly-bound states.

Vacuum ultraviolet spectra of heteronuclear dimers of inert gases in a direct-current discharge

The emission bands appearing near the resonance lines of Kr and Xe in the spectra of the gas-discharge plasma of binary Xe-X and Kr-Y mixtures (X is He, Ne, Ar, or Kr; Y is He, Ne, or Ar) are experimentally studied. It is concluded that the emission bands investigated are related to electronic transitions in hetero-nuclear dimers. The mechanisms of formation of the spectra under study are analyzed.

Energy relaxation and quenching processes of doped rare-gas clusters with a shell-like geometric structure

Energy relaxation processes of photo-excited Kr50¯ clusters covered with a shell of Ar atoms (up to 40), which are embedded inside large Ne7500¯ clusters are investigated with energy resolved fluorescence spectroscopy. In the energy range of the characteristic Ne cluster absorption (16.5–18 eV) a strong energy transfer to the embedded Kr cluster is observed, which results in the desorption of electronically excited Kr* atoms. Kr* atoms move through the Ne cluster, desorb and emit visible and near-infrared light in the vacuum (5p→5s). By coating the Kr clusters with Ar atoms, the Kr lines disappear and 4p→4s transitions of Ar* become dominant. Additionally, new emission bands occur, which are assigned to transitions of perturbed atomic Kr 5p-states inside Ne clusters. Due to the interaction of electronically excited Kr* atoms with neutral Ar atoms in the surrounding shell, several excited Kr states namely 5p [1/2]0 and 5p [3/2]2 decay nonradiatively. This is in agreement with the well-known “energy-gap law.” The results give experimental evidence that clusters with a multishell structure can be prepared by a sequential pick-up technique. This allows the preparation of Kr clusters embedded inside Ne clusters and coated with a shell of Ar atoms. Such clusters cannot be prepared with conventional coexpansion techniques.

Spectra of Laser Irradiated Xenon and Krypton in the Wavelength Range 0.5–1.0 nm

X-ray spectra of highly-ionized xenon and krypton measured in a laser-irradiated gas jet are presented with a main purpose of line identification. The spectral range of 0.5 to 1 nm was covered using two flat Bragg crystal spectrographs. The very rich spectra of xenon cover the transitions 3p–nd and 3d–nf, with n = 5 to 10, of Xe26+ to Xe30+ (Ni-like to Cr-like). Transitions 2p–nd and 2s–np with n = 3, 4 of Kr24+ to Kr28+ (Mg-like to O-like) have also been recorded, in a range covering some unidentified lines. Ab initio detailed calculations performed with the RELAC code have permitted to identify lines of Xe and Kr, including transitions which were measured but not identified until now. Ionic fractions were deduced by adjusting the experimental spectra with a least-squares fit based on the RELAC data.

Visible spectrum of highly charged ions: The forbidden optical lines of Kr, Xe, and Ba ions in the Ar I to Kr I isoelectronic sequence

We present experimental data on visible transitions in highly charged ions observed in the Lawrence Livermore National Laboratory (LLNL) electron beam ion traps, including results from lines within the ground-state configuration and the first excited configuration. Measurements of lines produced by Kr (q = 11+ to 22+), Xe (q = 18+ to 35+), and Ba (q = 28+ to 36+) ions, corresponding mainly to 3sl 3pm 3dn configurations, were carried out. The ionization stages were determined experimentally by sweeping the electron beam energy over the ionization threshold of each species. We propose possible identifications for the lines with the help of simple atomic structure calculations. However, most observed lines remained unidentified, demonstrating that the understanding of visible spectra from highly charged ions, even if obtained under nearly "ideal" experimental conditions, is still in its infancy. These spectral data may be useful for the diagnostics of magnetically confined plasmas and may set the stage for future measurements of radiative lifetimes. In our experiments, we used the emission from visible lines to image the intersection of the electron beam with a beam of neutral atoms injected into the trap at a right angle as well as the ion cloud in the trap. Under some conditions, the diameter of the ion cloud may be an order of magnitude larger than that of the electron beam. PACS Nos.: 32.30Jc, 39.30+w, 52.59Rz

Electron temperatures of inductively coupled Cl2–Ar plasmas

Trace rare gases optical emission spectroscopy has been used to measure the electron temperature, Te, in a high-density inductively coupled Cl2–Ar plasma at 18 mTorr as function of the 13.56 MHz radio frequency power and Ar fraction. Only the Kr and Xe emission lines were used to determine Te, because of evidence of radiation trapping when the Ar emission lines were also used for larger Ar fractions. At 600 W (10.6 W cm−2), Te increases from ∼4.0±0.5 eV to ∼6.0±2.0 eV as the Ar fraction increases from 1% to 96%. In the H (inductive, bright) mode, Te, for a “neat” chlorine plasma (including 1% of each He/Ne/Ar/Kr/Xe) increases only slightly from ∼3.8 to 4.0 eV as power increases from 450 to 750 W. This increase is much larger for larger Ar fractions, such as from ∼4.0 to 7.3 eV for 78% Ar. Most of these effects can be understood using the fundamental particle balance equation.