Experimental Line Strengths Research Articles

Transition probabilities and suitable coupling scheme for 6p→6s transition array of neutral xenon using hollow cathode discharge lamp technique

In the present work, analyses have been performed to determine spectroscopic parameters, including transition probabilities, and relative line strengths of discharge-produced xenon plasma. We present the transition probabilities of twenty-three emission lines originating from the 5p56p →5p56s transition array of neutral xenon covering the wavelength range from 450 to 1100 nm using a xenon-filled hollow cathode discharge lamp. The experimental absolute transition probabilities have been measured by combining the reported lifetimes of upper levels with the integrated spectral intensities of xenon transitions. The results agree well with the reported data in the NIST database, where available. The theoretical line strengths for all spectral transitions originating from the 5p56p→5p56s transition array have been calculated in the LS, LK, jj, and jck coupling schemes using the 3j, 6j, and 9j symbol relations. Furthermore, the normalized experimental line strengths have also been measured and compared with theoretical line strengths, which confirm that the jj and jck coupling scheme is more appropriate for the level designation of xenon.

Spectroscopic analyses of Er3+/Yb3+ co-doped laser sintering silica glasses

In this study, the laser sintering technique was used to obtain Er3+/Yb3+ co-doped silica glasses for up-conversion (UC) luminescence for the first time. Further, structural analysis of the glass sample was conducted via XRD, SEM and EDS measurements. Based on the measured absorption spectrum, important spectroscopic parameters including three intensity parameters Ωt (t = 2, 4 and 6), theoretical and experimental line strengths, spontaneous transition probabilities, branching ratios and radiative lifetimes, were calculated using the Judd-Ofelt (J-O) theory. The UC properties of Er3+/Yb3+ co-doped silica glasses were investigated upon the excitation of a 976 nm laser. It has been experimentally confirmed that the green and red UC luminescences corresponding to the radiative transitions of Er3+: 2H11/2 → 4I15/2 (green), 4S3/2 → 4I15/2 (green) and 4F9/2 → 4I15/2 (red) were achieved. This result is consistent with those of the J-O theoretical analysis. Additionally, the energy transfer mechanism between Er3+ and Yb3+, which is responsible for the UC process, was discussed based on their dependence on the pump power. The obtained results indicated that the Er3+/Yb3+ co-doped silica glasses manufactured using the laser sintering technique can be promising for the application of short-wavelength lasers.

Line strength analysis of the second overtone [formula omitted] band of D[formula omitted

The high resolution infrared spectrum of di–deuterated hydrogen sulfide D2S was recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and analyzed in the region of 2400–2900 cm−1 where ro–vibrational bands of the so–called second triad of D2S are located. The present study is focused on the line strength analysis of the weak 3ν2 band which is made for the first time. The strength analysis comprise 300 lines (376 transitions) with maximum values of the quantum numbers Jmax = 18 and Kamax = 9 and was performed by the fit of the experimental line shapes with a Hartmann–Tran profile. The six effective dipole moment parameters of the 3ν2 band were obtained from the weighted fit which reproduce the initial experimental line strengths with the drms=3.1%.

Line strengths, widths and shifts analysis of the [formula omitted][formula omitted] and [formula omitted] bands in [formula omitted]SiH[formula omitted][formula omitted]SiH[formula omitted] and [formula omitted]SiH[formula omitted

The high resolution infrared spectra of SiH4 in its natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm−1 and analyzed in the region of 1600–2100 cm−1 where the first bending overtone 2ν2,2ν4 and combinational ν2+ν4 bands are located. A line strength analysis of the 2018 (1636/211/171) experimentally recorded transitions of the 28SiH4,29SiH4, and 30SiH4 species was made by the fit of their line shapes with the Hartmann-Tran profile and 9 effective dipole moment parameters (7/1/1 fitted parameters for the 28SiH4,29SiH4 and 30SiH4 species, respectively) were obtained from the weighted fit which reproduce initial experimental line strengths of 28SiH4,29SiH4 and 30SiH4 with the drms=3.65%,3.77% and 3.46%. Self–broadening coefficients of 1064 lines (typically lying between (8 and 10)×10−2 cm−1·atm−1) and self–shift coefficients of 785 lines (typically lying between (5 and 10)×10−3 cm−1·atm−1) of all three isotopologues of silane were determined from the multi–spectrum analysis of these lines.

Comprehensive study of the pentad bending triad region of germane: Positions, strengths, widths and shifts of lines in the [formula omitted][formula omitted] and [formula omitted] bands of [formula omitted]GeH[formula omitted][formula omitted]GeH[formula omitted][formula omitted]GeH[formula omitted][formula omitted]GeH[formula omitted][formula omitted]GeH[formula omitted

The high resolution infrared spectra of GeH4 in its natural abundance were recorded with a Bruker IFS125 HR Fourier transform infrared spectrometer at an optical resolution of 0.003 cm−1 and analyzed in the region of 1400–2000 cm−1 where the first bending overtone 2ν2,2ν4 and combinational ν2+ν4 bands are located. Ro–vibrational line positions and energies of the 70GeH4 species were analysed for the first time and line positions and energies of the 72GeH4 and 74GeH4 species were improved considerably in comparison with the preceding studies. The numbers of 2316/2406/873/3007/2257 transitions with Jmax = 21/23/18/22/19 of the 2ν2 (A1− and E−type sub–bands), 2ν4 (A1−,E− and F2−type sub–bands) and ν2+ν4 (F1− and F2−type sub–bands) bands of the 70GeH4,72GeH4,73GeH4,74GeH4, and 76GeH4 molecules were used in the joint weighted fit of experimentally assigned transitions with the Hamiltonian model which takes the resonance interactions between the seven, (0200,A1),(0200,E),(0101,F1),(0101,F2),(0002,A1),(0002,E) and (0002,F2), vibrational states into account. From our preceding studies 5563 hot band transitions were also taken into account. As the result of a joint fit, a set of 129 fitted parameters was obtained which reproduce the initial 16422 experimental (including “hot”) transitions of five isotopologues with the drms=3.26×10−4 cm−1. A line strength analysis of the 1697 experimentally recorded transitions of all species was made by the fit of their line shapes with the Hartmann-Tran profile and 13 effective dipole moment parameters were obtained from the weighted fit which reproduce the initial experimental line strengths with the drms=3.4%. Self–broadening coefficients of 993 lines and self–shift coefficients of 674 lines were determined from the multi–spectrum analysis of these lines.

Ro–vibrational analysis of the first hexad of hydrogen sulfide: Line position and strength analysis of the 4ν2 band of H232S and H234S for HITRAN applications

The high resolution infrared spectrum of hydrogen sulfide H232S was recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and analyzed in the region of 4400–5400 cm−1 where ro–vibrational bands of the so–called first hexad of hydrogen sulfide are located. The present study is focused on the weak 4ν2 band. The 505 transitions with maximum values of the quantum numbers Jmax=17 and Kamax=8 (Jmax = 9 and Kamax=7 in the preceding studies) were assigned in the experimental spectrum. On this basis, 132 upper ro–vibrational energies (which is 2.5 times as high as in the preceding studies) were obtained. These data were used in the weighted fit of the Watson Hamiltonian parameters. The 28 varied parameters reproduce the 132 initial energy values with the root mean square deviation drms=3.5×10−4 cm−1. Strength analysis of the 287 strongest experimentally recorded transitions was made by the fit of their line shapes with the Hartmann-Tran profile. The eight effective dipole moment parameters of the 4ν2 band were obtained from the weighted fit which reproduce the initial experimental line strengths with the drms=3.1%. A comparison of the obtained results with the results of variational calculations and HITRAN data is presented. For the first time, transitions of the 4ν2 band of H234S were assigned in the experimental spectrum.

Experimental line strengths of the 5ν2 band of H[formula omitted]S in comparison with the results of “variational” calculation and HITRAN database

The strengths of 176 transitions of the 5ν2 band of H232S were experimentally recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer and theoretically analyzed. The seven effective dipole moment parameters of this band were obtained from the weighted fit which reproduce the initial experimental line strengths with the drms = 3.4%. A comparison of the obtained results with the results of variational calculation and HITRAN data is presented.

Extended analysis of the lowest bands of 12C2H4: Line strengths, widths, and shifts in the ν7, ν10, and ν4 bands

The high–resolution infrared spectra of 12C2H4 were analyzed in the region of 600 – 1200 cm−1, where the ν7, ν10, and ν4 bands are located. 2259 line strengths (3369 transitions) were determined from the fit of their line shapes with a Hartmann–Tran profile (Jmax=46 and Kamax=19) which is about two times higher than in preceding studies. These data were used in the fit of the effective dipole moment parameters and eight such parameters (5 parameters of the ν7 band and 3 parameters of the ν10 band) were obtained in the frame of the improved effective dipole moment model which reproduce the strengths of the initial lines with the drms=4.18%. Pressure self–broadening coefficients of 594/303 lines and self–shift coefficients of 344/227 lines for the ν7 and ν10 bands were determined from the multi–spectrum analysis. The line list of 3369 transitions with the experimental line positions and strengths is documented.

First quantitative study of the high-resolution spectrum of 28SiD4 in the region of the ν3 band: Line strengths and widths

Individual strengths of 358 (Jmax=28) ro-vibrational lines of the ν3 band of 28SiD4 were obtained from an experimental Fourier transform spectrum by the fit of their shapes with the Hartmann–Tran line profile. They were used in the weighted fit for determination of the effective dipole moment parameters of the ν3 band. Three effective dipole moment parameters were obtained which reproduce the experimental line strengths with the drms=4.0%. A list of 8125 transitions of the ν3 band with their line strengths was calculated up to J=43. The half-widths analysis was made on the basis of the multi-spectrum fit with the Hartmann–Tran line profile. Self line broadening coefficients were estimated for 72 isolated lines of the ν3 band.

Fourier-transform-spectroscopic photoabsorption cross sections and oscillator strengths for the S2 BΣu-3-XΣg-3 system.

Photoabsorption cross sections and oscillator strengths for the strong, predissociating vibrational bands, v ≥ 11, in the S2 BΣu-3-XΣg-3(v,0) system are reported. Absorption measurements were undertaken on S2 vapor produced by a radio-frequency discharge through H2S seeded in helium, and also in a two-temperature sulfur furnace, at temperatures of 370 K and 823 K, respectively. S2 column densities were determined in each source by combining experimental line strengths in low-v non-predissociating B - X bands (v < 7) with calculated line f-values based on measured radiative lifetimes and calculated branching ratios. The broad-band capabilities of two vacuum-ultraviolet Fourier-transform spectrometers, used with instrumental resolutions of 0.22 cm-1 and 0.12 cm-1, respectively, allowed for simultaneous recordings of both non-predissociating and predissociating bands, thus placing the predissociating-band cross sections on a common absolute scale. Uncertainties in the final cross section datasets are estimated to be 15% for the 370-K vapor and 10% for the 823-K vapor. The experimental cross sections are used to inform a detailed predissociation model of the B(v) levels in Paper II [Lewis et al., J. Chem. Phys. 148, 244303 (2018)]. For astrophysical and other applications, this model can be adjusted simply to provide isotopologue-specific cross sections for a range of relevant temperatures.

Spectroscopic properties of lanthanide based metal-organic framework [Nd(C4H5O6)(C4H4O6)][3H2O]: Theoretical and experimental approaches

The spectroscopic properties of a lanthanide based MOF, [Nd(C4H5O6)(C4H4O6)][3H2O] have been discussed in detail. Semiempirical quantum methods are used to calculate the singlet and triplet excited states, and Uv and IR spectra of the organic part of the MOF. The experimental absorption and luminescent spectra of the MOF are also reported. The experimental absorption spectrum shows the characteristic transition of Nd(III) ion as well as the transitions of the ligands. The experimental line strengths of all the observed transition are calculated. The standard Judd-Ofelt theory is used to calculate intensity parameters, transition probabilities, branching ratios, and radiative lifetimes for [Nd(C4H5O6)(C4H4O6)][3H2O] MOF. The JO parameters are used to calculate various excited state properties. Upon excitation by ultraviolet and visible photons, the complex emits in blue and green regions respectively. The blue emission is ligand (tartrate) based assigned to S1→ S0 transition whereas green emission is metal based assigned to 4G9/2 + 4G7/2 → 4I11/2 transitions. No antenna effect is observed in NTT-MOF. It is because of the large gap between the triplet energy level of the tartrate ligand and the resonance energy level 4F3/2 of the Nd(III) ion.

Transition probabilities, oscillator strengths, and test ofJ-file sum rule for the 2p53p → 2p53s transition array in the neon emission spectra

In this work experimental transition probabilities, line strengths, and atomic oscillator strengths of 30 spectral lines corresponding to the 2p53p → 2p53s transitions array of neon have been deduced using a neon-filled hollow cathode lamp in conjunction with two spectrographs covering the wavelength region from 500 to 1000 nm. The experimental absolute transition probabilities have been determined using the relative intensity method and lifetimes of the excited states. The transition probabilities have been converted to the line strengths data and used for testing the J-file sum rule. Relative line strengths of all the lines have been computed to determine the oscillator strength values. The measured transition probabilities, oscillator strengths, and relative line strengths agree well with the previously reported data.

Experimental relative line strengths within selected multiplets of neutral sulfur from the visible and infrared spectral range

In a wall-stabilized cascade arc helium plasma with some traces of SF6 has been generated. On the basis of measured total line intensities emitted from the plasma, the relative line strengths within twelve multiplets of neutral sulfur (SI) have been determined. The studied lines cover the spectral range from 415 nm to 1046 nm. The obtained experimental line strengths are compared with results of recent theoretical data as well as with results of older experiments. In addition the SI line strength data are compared with analogous transitions in the OI spectrum.

Estimation of low-temperature spectra behavior in Nd-doped Sc_2SiO_5 single crystal

High optical quality Nd-doped Sc(2)SiO(5) crystal with size of diameter 27 mm x 60 mm was obtained by Czochralski method. An x-ray diffraction pattern of Nd:SSO crystal confirmed that the as-grown crystal was isostructual with the SSO crystal. Absorption and emission spectra were recorded at 10 K. The Judd-Ofelt theory was applied to obtain standard parameters Omega t(t=2,4,6) and the fitting result of experimental absorption line strengths, which provided the F3/24 radiative lifetime (tau(rad)) of 219 micros and the luminescence branching ratio beta of 0.57 for the (4)F(3/2)-(4)I(9/2) laser transition. The stimulated emission cross section of 1.04 x 10(-19) cm(2) at 1074 nm was calculated using the Füchtbauer-Ladenburg equation. The (4)F(3/2) luminescence lifetimes with 215 micros at 10 K and 198 micros at 300 K were determined from luminescence decay curves, indicating high quantum efficiency in the Nd:SSO crystal. All these results showed that Nd:SSO would be a promising gain media in solid-state lasers.

Simulation of two-photon absorption spectra of [formula omitted] by direct calculation

Two-photon absorption (TPA) line strengths for transitions within the 4 f 7 configuration of Gd 3 + have been successfully calculated with several different time-independent perturbation methods. However, attempts to use similar methods to predict TPA line strengths for transitions within the 4 f 7 configuration of Eu 2 + have been much less successful, due to the fact that the low-lying 4 f 6 5 d excited states make straight-forward application of perturbation theory unreliable. In this work we carry out a direct calculation of TPA line strengths that take into account the major interactions for 4 f 7 and 4 f 6 5 d configurations nonpertubatively. We also calculate the linewidths of TPA peaks due to nonradiative relaxation to 4 f 6 5 d energy levels by considering the odd parity vibrations responsible for nonradiative relaxation. Comparisons of calculated TPA line strengths and linewidths with experimental spectra allow improved energy-level assignments. The calculated TPA spectra give a good reproduction of the experimental line strengths, polarization dependences, and linewidths.

Broadening and line mixing in the 20 (0)0

Using both a difference frequency spectrometer and a Fourier transform spectrometer, we have measured transitions in the 12 (2)0<--01 (1)0 band of carbon dioxide at room temperature and pressures up to 19 atm. The low-pressure spectra were analyzed using a variety of standard spectral profiles, all with an asymmetric component to account for weak line mixing. For this band, we have been able to retrieve experimental line strengths and the broadening and weak mixing parameters. In this paper we also compare the suitability of the energy-corrected sudden model to predict mixing in the two previously measured Q branches 20 (0)0<--01 (1)0, the 11 (1)0<--00 (0)0, and the present Q branch of pure CO(2), all at room temperature.

Spectra, energy levels, and transition line strengths forSm3+:Y3Al5O12

Optical spectra and energy levels of the sextet, quartet, and doublet states of ${\mathrm{Sm}}^{3+}$ ${(4f}^{5})$ incorporated into single crystals of ${\mathrm{Y}}_{3}{\mathrm{Al}}_{5}{\mathrm{O}}_{12}$ $({\mathrm{Sm}}^{3+}:\mathrm{Y}\mathrm{A}\mathrm{G}),$ where YAG denotes yttrium aluminum garnet, are reported and analyzed at wavelengths between 560 and 280 nm. The analysis of energy (Stark) levels is based on a model Hamiltonian consisting of Coulombic, spin-orbit, and interconfigurational terms for the ${4f}^{5}$ atomic configuration of ${\mathrm{Sm}}^{3+}$ and crystal-field terms in ${D}_{2}$ symmetry (the site symmetry of the ${\mathrm{Sm}}^{3+}$ ions in the garnet lattice). The Hamiltonian also includes contributions arising from the spin-correlated crystal field. Because of the strength of the crystal field, the entire energy matrix is diagonalized within the complete ${4f}^{5}$ ${\mathrm{SLJM}}_{J}$ basis set representing 73 LS states, 198 ${}^{2S+I}{L}_{J}$ multiplets, and 1001 doubly degenerate crystal-quantum states. In ${D}_{2}$ symmetry, all Stark levels are characterized by the same irreducible representation ${(}^{2}{\ensuremath{\Gamma}}_{5}).$ Optimization between 314 calculated-to-observed Stark levels was carried out with a final rms deviation of 10 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$. Eigenvectors obtained from the crystal-field splitting analysis are used to calculate transition line strengths originating from the ground-state Stark level to Stark levels in excited manifolds. The calculated line strengths are compared with experimental line strengths obtained from the absorption spectrum at 3.8 K. The line-strength analysis is useful in identifying individual excited Stark levels associated with sextet, quartet, and doublet states strongly mixed by the crystal field.

Water Vapor Measurements between 590 and 2582 cm−1: Line Positions and Strengths

This study involves measurements of H216O, H217O, and H218O vapor spectra for the region between 590 and 2582 cm−1. The parameters derived from the data include line positions, energy levels, and linestrengths. The study involves high-resolution line-position measurements with samples at room temperature in the (000)–(000), (010)–(010), and (010)–(000) bands. The experimental frequencies were used along with microwave, far-infrared, and hot water emission measurements in an analysis to obtain high-accuracy rotational energy level values in the (000), and (010) vibrational states of H216O forJ≤ 20. The experimental linestrengths were fitted by least squares to a model in which the dipole moment was represented as a series expansion containing up to 19 dipole moment matrix elements. The measurements in this work were more extensive than reported in prior studies by this author for the (010)–(000) band.

Statistics of electromagnetic transitions as a signature of chaos in many-electron atoms

Using a configuration interaction approach we study statistics of the dipole matrix elements (E1 amplitudes) between the 14 lower odd states with J=4 and 21st to 100th even states with J=4 in the Ce atom (1120 lines). We show that the distribution of the matrix elements is close to Gaussian, although the width of the Gaussian distribution, i.e. the root-mean-square matrix element, changes with the excitation energy. The corresponding line strengths are distributed according to the Porter-Thomas law which describes statistics of transition strengths between chaotic states in compound nuclei. We also show how to use a statistical theory to calculate mean squared values of the matrix elements or transition amplitudes between chaotic many-body states. We draw some support for our conclusions from the analysis of the 228 experimental line strengths in Ce [J. Opt. Soc. Am. v. 8, p. 1545 (1991)], although direct comparison with the calculations is impeded by incompleteness of the experimental data. Nevertheless, the statistics observed evidence that highly excited many-electron states in atoms are indeed chaotic.

The Water Vapor Linestrengths between 11 600 and 12 750 cm−1

The water vapor linestrengths in the region of the 3ν + δ resonance polyad of interacting vibrational states (the corresponding upper states are (310), (211), (112), (013), (131), (230), (032), and (051)) have been analyzed leading to accurate dipole moment transition parameters. The effective rotational Hamiltonian constants used to calculate the vibration–rotation wavefunctions (J.-M. Flaud, C. Camy-Peyret, A. Bykov, O. Naumenko, T. Petrova, A. Scherbakov, L. Sinitsa, 1994.J. Mol. Spectrosc.183,300–309) take into account both strong centrifugal distortion effects and dark states presence. These effects are known to be important for the highly excited vibrational states of water-like molecules. The input data set included the line intensities measured by Toth (R. Toth, 1994.J. Mol. Spectrosc.166,176–183) and the line intensities of the weak bands 2ν1+ 3ν2, 3ν2+ 2ν3, and 3ν1+ ν2derived from peak absorptions of a spectrum recorded at a pressure of 17.0 Torr and a path length of 434 m. The parameters of the effective dipole moment operator determined by least square fitting give a very satisfactory agreement with experimental values since the mean error for the 876 experimental linestrengths is only 3.9%. It is worth noticing that such an agreement could be reached only because high-order resonance couplings with dark states were explicitly taken into account.