Normal Incidence Vacuum Spectrograph Research Articles

Extension of the Pt III Analysis

Using a sliding spark and a 6.65 m normal incidence vacuum spectrograph, the third spectrum of platinum was analyzed. The transitions involving high-lying levels were studied. A total of 241 Pt III lines of the transitions from the levels of the 5d76p + 5d66s6p configurations in the region 728–2062 Å were classified, increasing the number of known Pt III lines to more than 1000. Ninety-one energy levels belonging mostly to the 5d66s6p configuration were added to Pt III. The odd Pt III levels were theoretically interpreted by means of multiconfiguration Dirak–Fock calculations and a least-squares fit of the calculated to the observed levels in the framework of the orthogonal parameters technique.

Critically Evaluated Atomic Data for the Au iv Spectrum

A spectral investigation of triply ionized gold (Au iv) has been carried out in the wavelength region of 500–2106 Å. The gold spectra were photographed at the National Institute of Standards and Technology, USA, on a 10.7 m normal incidence vacuum spectrograph (NIVS) using a sliding spark source as well as on a 3 m NIVS at the Antigonish laboratory in Canada with a triggered spark source. Our analysis is theoretically supported by the pseudorelativistic Hartree–Fock (HFR) formalism with a superposition of configuration interactions implemented in Cowan's suite of codes. Radiative transition parameters are also calculated using the HFR+CPOL (core polarization effects) model and the multiconfiguration Dirac–Hartree–Fock approach, and their comparisons are used to evaluate the transition rate data. All the previously reported levels of the 5d 8, 5d 76s, and 5d 76p configurations are confirmed, except one, and three are newly established. The missing 1 S 0 level of 5d 8 is now established at 55,277.8 cm−1. A total of 981 observed lines (E1 type), classified to 1031 transitions, including 133 newly identified, enabled us to optimize 139 energy levels. Several astrophysically important transitions, forbidden (M1- and E2-type) lines of 5d 8 and 5d 76s, are provided with their Ritz wavelengths and radiative parameters. A critically evaluated set of energy levels, observed and Ritz wavelengths along with their uncertainties, transition rates, and uniformly scaled intensities of Au iv lines have been presented. Also, large-scale atomic data to compute the opacity of Au iv in the kilonova ejecta have been supplemented in this work.

Energy levels, wavelengths and radiative rates for transitions in Hg-like Bismuth

The fourth spectrum of bismuth (Bi IV) has been investigated in the vacuum ultraviolet region. Recordings of bismuth spectra were made on a 3-m normal incidence vacuum spectrograph at Antigonish laboratory in Canada using a triggered spark light source. The theoretical interpretation for this spectrum was made with the pseudo-relativistic Hartree-Fock approach implemented in Cowan's code. The previous analysis of the energy level structure of Bi IV is confirmed and extended with the identifications of the 6p2 1S0 and 5d96s26p 3D2 levels, which were not reported earlier. Two new doubly excited configurations 6p6d and 6p7s were studied for the first time with the identification of 56 spectral lines. In total, 84 energy levels were located in the 5d10[6s2+ 6snp (n = 6, 7) + 6p2 + 6snd (n = 6, 7) + 6s5f], 6p6d, 6p7s, 5d96s2np (n = 6–10) and 5d96s2nf (n = 5–13) configurations, among which fifteen were newly established. A total of 552 spectral lines have now been classified in Bi IV in the region 193–5000 Å. We also present the optimized energy level values, transition rates and Ritz wavelengths along with their uncertainties evaluated using the least-squares fitting procedure.

Energy structure investigations in triply ionized mercury: Hg IV

We report energy level structure of triply ionized mercury (Hg IV). The spectrum was recorded on a 3-m normal incidence vacuum spectrograph in the wavelength region 300 – 2000 Å, using a triggered spark source at the spectroscopy laboratory, St. Francis Xavier University, Antigonish in Canada. Wavelength measurement and the corresponding uncertainties caused by calibration procedures are carefully analyzed. Based on the analysis of original measurements, the energy levels are optimized, which resulted in an improved set of energy level values. A complete disentanglement of the origin of these energy levels may well be impossible; therefore, new configurations have been extended in our theoretical calculations using Cowan's pseudo-relativistic Hartree-Fock code with superposition of interacting configurations. All preceding results were confirmed, and the 5d8(6d + 7s) mixed configurations have been newly established with the aid of experimental data supported by theoretical calculations. Along with the optimized energy eigenvalues, the observed and Ritz wavelengths, transition rates, and eigenvector compositions of Hg IV are also given. The energy level values were optimized using a computer code LOPT.

Spectral analysis and calculations of line parameters for Xe-like Ce V

Four-times ionized cerium (Ce V) is isoelectronic with neutral xenon, having 5s25p6 1S0, the only level in the ground configuration. Previously reported energy levels and line classifications of the 5s25p5 (4f+5d+6d+6s and 6p) configurations were evaluated empirically by means of extended calculations and Boltzmann plots. Here, we have added a new configuration 5s5p64f to the previously reported work. The spectrum was recorded on a 3 m normal incidence vacuum spectrograph in the 300–1240 Å region at the Antigonish laboratory (Canada). Theoretical calculations were performed using the pseudo-relativistic Hartree-Fock (HFR) configuration interaction method. The transition probabilities were calculated for the above-mentioned configurations. We also calculated the lifetimes of 5s25p54f metastable states using the MCDHF method.

Revised and extended analysis of doubly ionized bismuth: Bi III

The third spectrum of bismuth (Bi III) with its ground configuration 5d106s26p has been investigated in the wavelength region 278–2000 Å using spectrograms recorded on a 3-m normal incidence vacuum spectrograph. The observed spectrum was interpreted using semi-empirical calculations with Cowan's code in the framework of the quasi-Relativistic Hartree-Fock method. Analyses made by previous investigators on one and three-electron systems were checked thoroughly, while the tentative identification of the 2S1/2 level of the 5d106s6p2 configuration is confirmed. For the first time we had investigated the 6p3, 6s6p6d and 6s6p7s odd configurations based on the identification of 99 spectral lines. In total, 67 energy levels are now established in the 5d10[6s2np (n = 6–8) + 6s2nf (n = 5–7) + 6s2nh (n = 6–7)], 6s6p2 and 5d96s26p2 configurations, among which 23 energy levels were newly located. The least squares parametric fitting calculations were performed to interpret the final results of the analysis. Optimization of the observed energy levels was carried out with the computer program LOPT. The ionization energy was found to be 206,242.0 ± 1.4 cm−1 (25.5708±0.0002 eV).

Spectral analysis of triply ionized silver (Ag IV)

The spectral investigation of triply ionized silver (Ag IV) has been carried out in the vacuum ultraviolet region. Silver spectra excited through a triggered spark source were photographed on a 3-m normal incidence vacuum spectrograph at St. F. Xavier University, Antigonish in Canada. The theoretical study of the spectrum was made through the quasi-relativistic Hartree-Fock formalism in Cowan's code. The previous work of Ag IV on the 4d75p-(4d8+4d75s) transition array was confirmed but with some revisions. The study of a new transition array 4d7(5d+6s)-4d75p resulted in the establishment of 27 energy levels of 4d75d and 4d76s configurations. A total of 182 energy levels of 4d8, and 4d7nℓ (ℓ=0, 1, 2, and n=5, 6) configurations were optimized, through the classification of 1146 transitions.

Critically evaluated energy levels, wavelengths, transition probabilities, and intensities of six-times ionized cesium: Cs VII

Previously reported works on the spectrum of Cs VII are critically studied using supplementary spectrograms recorded on a 3-m normal incidence vacuum spectrograph in the wavelength region 300–1240 Å at the Antigonish laboratory (Canada). We confirmed the results of the earlier work of Gayasov and Joshi on this spectrum. Our analysis is supported by extended calculations with the pseudo-relativistic Hartree-Fock (HFR) method with superposition of configuration interactions implemented in Cowan's suite of codes. In this critical evaluation, in addition to the accurate energy levels of Cs VII with their uncertainties, observed and Ritz wavelengths with uncertainties and transition probabilities, the uniformly-scaled intensities of Cs VII lines are also presented. A total of 196 lines attributed to 197 transitions enabled us to optimize the energy values of 72 levels in Cs VII spectrum. Furthermore, Ritz wavelengths of 141 possibly observable lines are provided along with their transition probabilities.

Revised and extended analysis of doubly ionized gold: Au III

The spectrum of doubly ionized gold (Au III) photographed in the region 450–2106 Å has been investigated. The gold spectra have been recorded at two places viz. at the National Institute of Standards and Technology (USA) on a 10.7-m normal incidence vacuum spectrograph (NIVS) using a sliding spark source as well as on a 3-m NIVS at the Antigonish laboratory in Canada with a triggered spark source. Au III has a ground configuration [4f14]5p65d9 with 2D5/2 as its lowest level. Excited configurations are quite complicated as the first excited odd parity configuration 5d86p alone contains 45 energy levels. Excitation of a single electron from the valence 5d shell produces configurations of the type 5d8nl. Various configurations arise due to multiple excitation of the 5d9 subshell, e.g., 5d76s6p, 5d76s2, 5d66s26p, 5d76p2, etc. Theoretical predictions were made using Cowan's quasi-relativistic Hartree-Fock code with the superposition of configurations involving 5p6 [5d9 + 5d8ns (n = 6–8) + 5d8nd (n = 6–8) + 5d76l2(l = 0–2)+5d7(6s6d+ 6s7s+ 6d7s)] in the even parity system and 5p5 [5d10 + 5d96s] + 5p6 [5d8np (n = 6–8) + 5d8nf (n = 5–7) + 5d7 (6s6p+ 6s7p+ 6p7s+ 6p6d+ 6s5f+ 6s6f) + 5d66s26p] in the odd parity matrix. A total of 262 energy levels belonging to the 5d9 + 5d8[6s+7s+6d+6p] + 5d7[6s2 + 6s6p] configurations have been established, 69 being new including three revised levels, one from each of the 5d86d, 5d87s and 5d76s6p configurations. In the process, 1504 spectral transitions have been classified in the wavelength region 570–3310 Å. The accuracy of the wavelength measurements for sharp and unblended lines is ±0.005 Å. The final interpretation of the results was made on the basis of least squares fitted parametric calculations. The level optimization was achieved with a computer program LOPT.

Revised analysis of the third spectrum of mercury: Hg III

The doubly charged mercury (Hg III) is having the closed sub-shell 5d10(1S0) as its ground state and the first exited configuration(s) of the type 5d9nl (n ≥ 5). The spectrum of mercury was recorded on a 3-m normal incidence vacuum spectrograph at the spectroscopy laboratory of St. F. X. University in Canada. The excitation source used was a triggered spark in the wavelength region of 300–2000 Å. The theoretical calculations (inclusive of extended configurations) for the ion were accomplished by means of Cowan's quasi-relativistic Hartree-Fock code with superposition of configurations for appropriate interpretation of energy levels. Least squares fitted parametric calculations were used to elucidate the observed level structure. The obtained energy level values were optimized using a level optimization program (LOPT). A gross set of energy eigenvalues along with their LS-compositions, wavelengths and weighted transition probabilities of Hg2+ in the wavelength range 590 Å to 8200 Å are given. The ionization potential of Hg III was found to be 278,200 ± 400 cm−1 (34.49 ± 0.05 eV).

Revised and extended analysis of the third spectrum of silver: Ag III

The spectrum of doubly ionized silver (Ag III) having the ground configuration 4p64d9 has been investigated. The silver spectra were recorded on a 3-m normal incidence vacuum spectrograph at St. Francis Xavier University, Antigonish (Canada) using a triggered spark source. Theoretical predictions based on the Hartree–Fock method were made using superposition of interacting configurations and relativistic corrections. For proper interpretation of configuration interaction, the configurations 4p6[4d9, 4d8ns (n=5–9), 4d8nd (n = 5–9), 4d8ng (n=5–7), 4d75s2 and 4d75p2] and 4p54d10, 4p6[4d8np (n=5–7), 4d8nf (n = 4–6), 4d8nh (n = 6–7), 4d75s5p and 4d75s4f] were incorporated in the even and odd parity systems, respectively. The previous analyses were checked thoroughly; five levels of 4d85p were revised and two configurations, viz., 4d85d and 4d86s have been investigated for the first time. A total of 124 energy levels were established belonging to the configurations 4p6[4d9+4d8(5s + 6s + 5p + 5d)], among which 64 levels of 4p64d8(5d + 6s) were newly established. Least squares fitting parametric calculations were carried out to interpret the observed energy level structure. The observed energy levels were optimized to fit the measured wavelengths.

Spectral analysis of the fifth spectrum of indium: In V

The fifth spectrum of indium (In V) has been investigated in the grazing and normal incidence wavelength regions. In4+ is a Rh-like ion with the ground configuration 4p64d9 and first excited configurations of the type 4p64d8nℓ (n≥4). The theoretical predications for this ion were made by Cowan's quasi-relativistic Hartree–Fock code with superposition of configurations involving 4p64d8(5p+6p+7p+4f+5f+6f), 4p54d10, 4p64d75s(5p+4f) for the odd parity matrix and 4p64d8 (5s+6s+7s+5d+6d), 4p64d7(5s2+5p2) for the even parity system. The spectra used for this work were recorded on 10.7m grazing and normal incidence spectrographs at the National Institute of Standards and Technology, Gaithersburg, Maryland (USA) and also on a 3-m normal incidence vacuum spectrograph at Antigonish (Canada). The sources used were a sliding spark and a triggered spark respectively. Two hundred and thirty two energy levels based on the identification of 873 spectral lines have been established, forty six being new. Least squares fitted parametric calculations were used to interpret the observed level structure. The energy levels were optimized using a level optimization computer program (LOPT). Our wavelength accuracy for sharp and unblended lines is estimated to be within ±0.005Å for λ below 400Å and ±0.006Å up to 1200Å.

Extended and revised analysis of singly ionized tin: Sn II

The electronic structure of singly ionized tin (Sn II) is partly a one-electron and partly a three-electron system with ground configuration 5s25p. The excited configurations are of the type 5s2nℓ in the one-electron part, and 5s5p2, 5p3 and 5s5pnℓ (nℓ = 6s, 5d) in the three-electron system with quartet and doublet levels. The spectrum analyzed in this work was recorded on a 3 m normal incidence vacuum spectrograph of the Antigonish laboratory (Canada) in the wavelength region 300 Å–2080 Å using a triggered spark source. The existing interpretation of the one-electron level system was confirmed in this paper, while the 2S1/2 level of the 5s5p2 configuration has been revised. The analysis has been extended to include new configurations 5p3, 5s5p5d and 5s5p6s with the aid of superposition-of-configurations Hartree–Fock calculations with relativistic corrections. The ionization potential obtained from the ng series was found to be 118 023.7(7) cm−1 (14.633 07(8) eV). We give a complete set of critically evaluated data on energy levels, observed wavelengths and transition probabilities of Sn II in the range 888–10 740 Å involving excitation of the n = 5 electrons.

Extended analysis of fifth spectrum of bromine: Br V

The fifth spectrum of bromine (Br V) has been studied in the 200–2400Å wavelength region. The spectrum was photographed on a 3-m normal incidence vacuum spectrograph at the St. Francis Xavier University, Antigonish (Canada) and 6.65-m grazing incidence spectrograph at the Zeeman laboratory (Amsterdam). The light sources used were a triggered spark and sliding spark. The ground configuration of Br V is 4s24p. The excited configurations 4s4p2+4s2(4d+5d+5s+6s+7s+5g+6g)+4s4p(5p+4f)+4p24d in the even parity system and the 4p3+4s2(5p+6p+7p+4f)+4s4p4d+4s4p5s configurations in the odd parity system have been studied. Relativistic Hartree–Fock (HFR) and least squares fitted (LSF) parametric calculations have been used to interpret the observed spectrum. 99 levels of Br V have now been established, 43 being new. Among 394 classified spectral lines, 181 are newly classified. The level 4s27s 2S1/2 is revised. We estimate the accuracy of our measured wavelengths for sharp and unblended lines to be±0.005Å. The ionization limit is determined as 479,657±200cm−1 (59.470±0.025eV).

Extended analysis of three times ionized barium (Ba IV)

The fourth spectrum of barium (Ba IV) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph at Antigonish laboratory (Canada) in the wavelength region 300–2080Å using a triggered spark as an excitation source. The spectral analysis has been extended to include a new odd-parity configuration 5s25p46p. Previously reported levels of the ground configuration and the three lowest excited configurations (5s5p6, 5s25p45d and 5s25p46s) have been confirmed. All the J≥7/2 unknown levels of the 5s25p45d configuration and the (3P) 4P5/2 level of the 5s25p46s configuration have now been established through the identification of transitions from the levels of the 5s25p46p configuration, all of which have now been established. A configuration interaction Hartree–Fock calculation supports the analysis.

Spectral analysis of 5s25p2(6p+6d+7s) configurations of Ba VI

The sixth spectrum of barium (Ba VI) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph of Antigonish laboratory (Canada) in the wavelength region 300–2080Å using triggered spark as an excitation source. The spectral analysis has been extended considerably to include new configuration the 5s25p26p in odd parity matrix and the 5s25p26d and 5s25p27s configurations in even parity matrix. Previously reported levels of the ground configuration (5s25p3) and three lowest excited configurations the 5s5p4, 5s25p25d and 5s25p26s have been confirmed and the two unknown levels of the 5s25p25d configuration with J=9/2, have now been established through the identification of transitions from the 5s25p26p levels. All twenty one levels of the 5s25p26p configuration and twenty nine levels out of thirty six of the 5s25p26d and 5s25p27s configurations have now been established. Hartree–Fock calculations involving configuration interactions support the analyses. The accuracy of our wavelength measurement is ±0.005Å for sharp lines.

Revised and extended analysis of Br IV

The spectrum of three-times ionized bromine Br IV has been studied in the 319–2350Å wavelength region. The spectrum was recorded on a 3-m normal incidence vacuum spectrograph at the St. Francis Xavier University, Antigonish (Canada) and 6.65-m grazing incidence spectrograph at the Zeeman laboratory (Amsterdam). The light sources used were a triggered spark and sliding spark, respectively. The ground configuration of Br IV 3d104s24p2, the excited configurations 3d104s4p3+3d104s24p (4d+5d+6d+5s+6s+7s) in the odd parity system and 3d104s24p (5p+4f+5f)+3d104s4p2 (4d+5s)+3d104p4 in the even parity system have been studied. Relativistic Hartree–Fock (HFR) and least squares fitted (LSF) parametric calculations were used to interpret the observed spectrum. 120 Levels of Br IV have now been established, 58 being new. Among 424 spectral lines, 277 are newly classified. The levels 4s4p35S2, 4s24p4d 3F4 and 4p5p (3P0, 1, 3D1, 2, 3S1) are revised. We estimate the accuracy of our measured wavelength for sharp and unblended lines to be ±0.005Å. The ionization limit is determined as 385,390±100cm−1 (47.782±0.012eV).

Description and characterization of two multichannel photodetectors in the VUV spectral range

Two classes of multichannel photodetectors in the vacuum ultraviolet (VUV) spectral zone are described and characterized. VUV radiation emitted from a laser-produced plasma source and was dispersed by a 1-m near normal incidence vacuum spectrograph was monitored by either channel electron multiplier array/intensified photodiode detector (CEMA/IPDA) combination, or un-gated backside illuminated charge coupled device (CCD) array. Results indicate that both dark current and readout noise of the CCD detector compare very favourably with corresponding values quoted by the manufacturer of the device. The spectrometric system with the CCD detector in place produced a FWHM of about 0.045nm in comparison with 0.1nm obtained with the CEMA/PDA combination. The resolving power (λ/Δλ) of the system has a value of about 1800 at 80nm approximately 2.25 times that obtained with the CEMA/PDA.

Extended analysis of four-times ionized barium: (Ba V)

The fifth spectrum of barium (Ba V) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph at the Antigonish laboratory (Canada) in the wavelength region 300–2080Å using triggered spark as an excitation source. The spectral analysis has been extended considerably to include new configuration 5s25p36p in even parity configuration and, 5s25p36d and 5s25p37s in odd parity configuration. Previously reported levels of the ground configuration and three lowest excited configurations 5s5p5, 5s25p35d and 5s25p36s in Ba V have been confirmed and all the J≥4 unknown levels of 5s25p35d configuration have now been established through the identification of transitions from the levels of 5s25p36p configuration. All the levels of 5s25p36p configuration and thirty seven out of forty eight levels of the 5s25p36d and 5s25p37s configurations have now been established. A configuration interaction Hartree–Fock calculation supports the analysis.

Extended analysis of six-times ionized barium (Ba VII)

The seventh spectrum of barium (Ba VII) has been investigated using experimental recordings made on a 3-m normal incidence vacuum spectrograph in Canada in the wavelength region 300–2000Å. The data below 350Å was supplemented from the spectrograms recorded on a 10.7-m grazing incidence spectrograph of NIST laboratory USA. The sources used to excite the spectra in both the cases were triggered spark. Previously reported levels of 5s25p2, 5s5p3, 5s25p5d and 5s25p6s in Ba VII have been confirmed except the 1P1 level of 5s25p5d. The analysis has been extended considerably to include new configurations 5s25p6d and 5s25p7s in odd parity configuration and doubly excited configurations 5s25p6p, 5s25p4f, 5s25p5f, 5p4, 5s5p25d and 5s5p26s in even parity configuration. The 3F4 level of 5s25p5d configuration has now been established through the identification of transitions from 5s25p6p. In all, one hundred twenty-two levels have been established in this spectrum out of which ninety-two are new. A configuration interaction Hartree–Fock calculation supports the analysis.