The shape of the 11S0 − 21P1 Fano resonance in the H- photo-ionization continuum

The interaction between the discrete autoionized state 1s2p of negative hydrogen and the overlapping split-configuration continuum is described in terms of stationary perturbations of nonorthogonal states that are eigenstates of two different first-order approximations to the Hamilton operator for the system.The eigenfunctions for the split-configuration states are taken to be those of a free p electron outside a neutral hydrogen atom in the ground state. The eigenfunction adopted for the short-lived, closed 1s2p configuration is the product of two functions that belong to symmetric Hartree-Fock eigenfunctions for the 1s²¹S and 2p²¹D states, respectively. This eigenfunction defines that Hamilton-operator approximation, of which the 1s2p state is an eigenstate.An improved Hamilton operator defines two different, but not independent, perturbation functions, one of which is a measure of the instability of the 1s2p configuration. The width of the resonance is found, correspondingly, to be determined by the product of two different perturbation terms. They are calculated in a Hartree-type approximation and found to be small, in part due to an effect of the nonorthogonality of the unperturbed states.The mean position of the singlet and triplet P Fano resonances in the ground state absorption continuum of H^- is found to be close to that of the diffuse interstellar bands at λ4430 and λ4760, but the calculated distance is about four times that of the bands. With exchange neglected and the position of maximum absorption fixed at λ4430 the singlet P resonance is found to have a width of 43 Å at half maximum, a minimum on the short-wave-length side, and a top absorption coefficient of 7 × 10^-16 cm²/ion, corresponding to an f value equal to 0.27.Tables of Hartree-Fock functions for the 2s²¹S, and the 2p²¹S, ¹D and ³P states of H^-, calculated by Claus Ingemann-Hilberg, are given in an appendix.     

Determination of the isotope shift in theD 1 line between197Au and195Au

The isotope shift between¹⁹⁷Au (stable) and¹⁹⁵Au (T _1/2=183 d) was determined by resonance fluorescence and polarization spectroscopy in the 6s² S _1/2 -6p ² P _1/2, λ =267.6nm line. The result is δν^{195, 197}=-2.9(2) GHz corresponding to a change of the mean-square charge radius by δ〈r ²〉^{195, 197}=0.063(9) fm². The sample was confined to a resonance cell heated to temperatures of up to 1500°C.     

Stark-Effekt-Verbreiterung der Neon I-Übergänge mit schwacher Feldstärkeabhängigkeit (2p 5 3s-2p 5 3p)

The half widths of Stark-broadened Ne I spectral lines (2p ⁵ 3s-2p ⁵ 3p) were measured in wall stabilized arc plasmas (pressurep=1 atm, andp=3 atm) consisting of several gas components (Ar 68%, Ne 27%, He 3%, H₂ 2%). The theoretical half widths of two spectral lines (λ=6,266.50 Å,λ=6,163.59 Å) with known calculated broadening parameters according to Griem differ by a factor 1.8 to 1.9 from the measured widths. Within the errors of Griem's line broadening calculations of about 20% there was agreement between experimental and theoretical half widths regarding two other spectral lines (λ=5,881.90 Å,λ=5,852.49 Å). Calculated adiabatic widths are smaller than the widths according to Griem. Therefore in some cases the deviation of the adiabatic widths from the measured widths is smaller than the difference between Griem widths and experimental ones. Static quadratic coefficients of NeI transitions 2p ⁵ 3s-2p ⁵ 3p calculated from measured Stark-broadened lines showed wavelength displacements in the order of 0.005 Å referring to an electrical field of 100 kV/cm. The determined coefficients are 10² times smaller than those values measurable by known methods of emission spectroscopy.     

Experimental transition probabilities of some Xe(I) lines

Using the light absorption technique in a ¹³²Xe afterglow plasma, we have measured the relative transition probabilities for several xenon lines which have the metastable 6s[$\text{3}\text{2}$]₂ or the resonant 6s[$\text{3}\text{2}$]₁ states as their lowest transition level. Because the transition probabilities of the 8819 Å (6p[$\text{5}\text{2}$]₃ ? 6s[$\text{3}\text{2}$]²) and 8280 Å (6p[$\text{1}\text{2}$]₀ ? 6s[$\text{3}\text{2}$]₁) lines are relatively well known, we have chosen these as reference lines and have thus been able to determine the absolute values of the transition probabilities for 19 xenon lines corresponding to transitions from 6p, 6p′, 7p, 8p, 9p, 4f and 5f to 6s[$\text{3}\text{2}$]₂, and for four lines corresponding to the transitions 6p?6s[$\text{3}\text{2}$]₁.     

Theoretical study of photoionization of the isoelectronic sequence Rb<Superscript>+</Superscript>, Sr<Superscript>2+</Superscript>, and Y<Superscript>3+</Superscript>

The photoionization cross sections for the 4p shell of ions of the Kr isoelectronic sequence Rb⁺, Sr²⁺, and Y³⁺ are calculated. The configuration interaction theory and the perturbation theory are used to describe the many-electron effects. The relativistic effects are taken into account in the Pauli-Fock approximation. The calculated resonance structure of photoionization cross sections for the 4p shell in the region below the 4s threshold associated with the autoionization of the 4s-np singly excited states and the 4p4p-nln′l′ doubly excited states reproduces the results of recent measurements of total photoabsorption cross sections for the Rb⁺, Sr²⁺, and Y³⁺ ions. It is found that, as the nuclear charge in the isoelectronic sequence increases, the ratio between the direct and correlation parts of amplitudes of the 4s-(n/?)p transition changes and, as the consequence, the minimum of the photoionization cross section of the 4s shell shifts from the continuous spectrum to the region of states of discrete spectrum. This accounts for the strong changes in the shape of the 4s-np resonances in the photoionization cross sections for the 4p shell of Rb⁺, Sr²⁺, and Y³⁺, as well as the distinction between the shapes of the 4s-6p _1/2 mirror resonance in the partial 4p _1/2 and 4p _3/2 photoionization cross sections for the Y³⁺ ion which do not suppress each other in the total photoionization cross section, as is the case for similar resonances in Rb⁺ and Sr²⁺.     

Atomic parameters for carbon-like S XI

Radiative rates and collision strengths of S XI are presented for 46 levels of configurations 2s²2p², 2s2p³, 2p⁴, 2s²2p3s, 2s²2p3p, and 2s²2p3d.     

Quenching kinetics and small signal gain spectrum of the ZnI photodissociation laser

By photodissociation ZnI₂ with 193 nm (ArF) laser radiation, the rate constants for quenching of the upper and lower energy levels of the ZnI (B → X) laser by ZnI₂ have been measured to be (1.7 ± 0.2) × 10^-9 and (1.4 ± 0.4) × 10^-9 cm³ s^-1, respectively. Although the former rate constant was found to be laser intensity-dependent for I ? 10⁵ W cm^-2, the ZnI(B) state radiative lifetime was determined to be 26 ± 4 ns. Also, the small signal gain coefficient, g₀, of this molecular laser has a peak value of ? 15% cm^-1 at λ ? 602 nm and exceeds 5% cm^-1 for 591 nm ≤ λ ≤ 608 nm for a potential tuning range of at least 170 Å.     

Energy Levels, Transition Probabilities, Collision Strength, and Reduced Population Calculations for High Gain Predictions in Neon-Like Krypton

We calculate the atomic structure, energy levels, oscillator strengths, transition probabilities, and collision strengths for Kr XXVII. The data refer to the 157 fine-structure levels belonging to the configurations (1s²) 2s² 2p⁶, 2s²2p⁵3l, 2s¹2p⁶3l, 2s²2p⁵4l, 2s¹2p⁶4l, 2s²2p⁵5l, and 2s¹2p⁶5l, where l?=?s, p, d, f, and the calculations are performed using the fully relativistic atomic structure program FAC. We use the obtained data to calculate the level populations and gain coefficients employing the MATLAB R2012a computer program for solving simultaneously the coupled rate equations. Finally, we determine the 157 fine-structure population levels and gain coefficients for those transitions with a positive inversion factor and plot the electron density in wide range from 10¹⁹ to 10²³.     

Extended measurements of isotope shifts in Mg I

The isotope shifts in the Mg I transitionsλ 2,852 Å (3s ^{2 1} S ₀-3s3p ¹ p ¹ P ₁) andλλ 3,829, 3,832 and 3,838 Å (3s3p ³ P-3s3d ³ D) have been measured for²⁴Mg,²⁵Mg and²⁶Mg. The measurements were carried out using a pressure scanned Fabry-Perot interferometer and separated isotopes excited in hollow cathode discharge tubes. The results are compared to theoretical predictions and an attempt is made to convert measured line shifts into level shifts.     

Relativistic atomic level calculations with nuclei carrying additional fractional charges

One-electron energy levels and wavelengths have been calculated for Na-like ions whose nuclei carry quarks with additional charges ±e/3, ±2e/3. The calculations are based on relativistic self-consistent field procedures. The deviations from experimental values exhibit regularities which allow an extrapolation for the wavelengths of 3s-3p, 3s-4p, 3p-3d, and 3p-4s transitions for the nuclear chargeZ=11+1/3, ±2/3. A number of transitions are found in the region of visible light which could be used in an optical search for quark atoms.     

Use of harmonic oscillator potential in the analysis of muonic transition energies

Energy levels: 1s _1/2, 2p _1/2, 2p _3/2, 3d _3/2, and 3d _5/2 of the muon in the spherical nuclei:¹²⁰Sn,¹⁹⁷Au and²⁰⁸Pb have been calculated under the assumption of harmonic oscillator potential. The levels are corrected for vacuum polarisation. The agreement with experimental values is better than 0·5%. An accurate method of solving the Dirac equation to obtain the energy eigenvalues is outlined. The importance of choosing the ‘classical turning point’ as the radius for matching the interior and exterior solutions is discussed.     

Experimental determination of isotope shifts in Mg I

The isotope shift in the Mg l transitionsλλ 5167, 5172 and 5183Å (3s3p ³ P-3s4s ³ S) andλ 5528 Å (3s3p ¹ P 3s4d ¹ D) has been measured for the isotopes²⁴Mg,²⁵Mg and²⁶Mg. The hyperfine structure of theλ 5167 Å line has been studied and theA andB factors for the 3s4s ³ S ¹ level in²⁵Mg determined. The measurements were made with separated isotopes using a scanning Fabry-Perot interferometer.     

Energy levels of ions of silver and rhodium isoelectronic sequences with <Emphasis Type="Italic">Z</Emphasis> < 86

The method of extrapolation of the parameter of a model potential for states of one electron (4f, 5s, 5p, 5d, 5f) above the core 1s ²2s ²2p ⁶3s ²3p ⁶3d ¹⁰4s ²4p ⁶4d ¹⁰ and one vacancy (4d ⁹) in the same core is applied to calculate the energy levels in the silver and rhodium isoelectronic sequences with the maximum nuclear charge Z = 86. The energy levels of Ag-and Rh-like ions were used for the calculation of the energies of resonance transitions to the ground state ¹ S ₀ in Pd-like ions. Good agreement between the theoretical and calculated energies of the resonance transitions in Pd-like ions indicates the reliability of the results obtained.     

A coupled-channels treatment of the positive-parity resonances in4He

The coupled-channels formalism, which has been previously applied successfully to interpret the negative-parity resonances in⁴He, has now been extended to the positiveparity 2?ω resonances in this system. The 1p-1h approach has been modified to include coupling to the 2p-2h configurations, which also belong to 2?ω excitations, by using the effective operator formalism. The effect of the Pauli term in thes-wave channel is examined and is found to be important in reproducing the 0⁺,T=0 resonance energy and width. Resonances with spins up toJ ^π=3⁺ have been studied, and the agreement with available data is satisfactory. In particular, from the good fit to the asymmetry coefficientβ(E), one establishes the presence of a 2⁺,T=0 resonance around 35-MeV excitation in the system.     

Determination of alignment tensor components for the H(2p) charge exchange excitation in proton-argon collisions

Alignment tensor components 〈T(L) _KQ ⁺ 〉 have been determined for the H(2p) charge exchange excitation in proton-argon collisions at an incident proton energy of 1.5 keV, and scattering angles Θ _s =4.3°, 4.9°, and 6.0°. It is demonstrated that the measured photon angular distribution cannot be described in terms of only λ and ? parameters.     

Dielectronic recombination of lithium-like gold: Towards QED tests

Dielectronic recombination (DR) and radiative recombination (RR) of lithium-like gold in the energy range of 0 to 225 eV have been studied at the Experimental Storage Ring (ESR) of the GSI in Darmstadt. Main objective of the measurements is the precise determination of the 2s_1/2−2p_1/2 energy splitting as an additional QED test. This novel method, developed at the ESR [1], is based on the extrapolation of a multitude of measured resonances Au⁷⁵⁺ (1s²2p_1/2 nl_j) up to the series limit (n = ∞). Furthermore experimental data for the Au⁷⁵⁺ (1s²2p_3/26l_j) resonance manifold are presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

RuXIV离子能级和振子强度的理论计算

利用组态相互作用理论和参数外推方法,计算RuXIV离子4s²4p,4s4p² 4s²4d和4p³组态的能级,以及4s²4p—4s4p²,4s²4p—4s²4d和4s4p²—4p³跃迁的谱线波长和振子强度。4s²4p和4s4p²组态的能级与已有实验 关键词：     

The kinetics of the sensitized flourescence of naphthalene single crystals doped with 2-methylnaphthalene and anthracene

The kinetics of the sensitized flourescence in naphthalene crystals doped with 2-methylnaphthalene (2-MN) and anthracene (A) was studied as a function of the temperature. These experiments yield singlet exciton diffusion constants of (2 ± 1) × 10^-4cm²s^-1 at 4.2 K and roughly 10^-5 cm² s^-1 at 300 K. The exciton trapping radii can be estimated to be of the order of 60 Å for A and 10 Å for 2-MN. At temperatures below 40 K a partially coherent exciton motion can be inferred, above 40 K the exciton motion appears to be purely incoherent.     

Laser induced line narrowing in three-level systems: Application to the determination of the wavenumber of the 3s2-2p4 neon line (λ = 6328 Å)

The Doppler-free absorption line narrowing technique (A.L.N.) is applied to the ²⁰Ne (3s₂-2p₄-1s₅) three-level system, using a ¹²⁷I₂ stabilized He-Ne laser (λ = 6328 Å) and a tunable single-frequency cw dye laser (λ = 5945 Å). The relative frequency positions of the ²⁰Ne 3s₂-2p₄ line and of some iodine hyperfine components are measured with an uncertainty of 1 MHz. The wavenumber of the ²⁰Ne line at low pressure (0.2 Torr) is deduced from these measurements and is found to be σ(²⁰Ne, 3s₂-2p₄) = 1579800.060 ± 0.005 m^-1. With regard to the previous results, the accuracy is increased by two orders of magnitude.