Hollow Cathode Lamp Research Articles

Experimental Radiative Lifetimes, Branching Fractions, and Oscillator Strengths of Some Levels in Er i and Er ii

Abstract Radiative lifetimes for 104 levels of Erbium (Er) i in the energy range between 31,926.003 and 44,525.705 cm−1 and 51 levels of Er ii from 31,381.779 to 47,840.962 cm−1 were measured by a time-resolved laser-induced fluorescence method. Branching fraction (BF) determinations for 356 lines from 47 out of 104 Er i levels and 122 lines related to 19 out of 51 Er ii levels were completed based on the emission spectra of hollow cathode lamps recorded using the 1.0 m Fourier transform spectrometer and are available from the digital library of National Solar Observatory on Kitt Peak, USA (http://diglib.nso.edu/). By combining these BFs and the lifetime results measured in this work, absolute transition probabilities and oscillator strengths were determined for 352 lines of Er i and 92 lines of Er ii for the first time, increasing the total number of lines with experimental transition probabilities to over 910 for Er i and over 540 for Er ii.

Высокостабильный источник спектральных линий

In spectroscopy, hollow cathode lamps are subject to increased requirements on radiation parameters. In order to perform verification of such lamps a highly stable source of spectral lines is needed, the intensity of which on the spectral lines will remain unchanged (≤1%) for a long time. A solution to this problem is proposed and a scheme of an experimental bench for a hollow cathode lamp with a negative feedback loop is presented. The developed device is used in control circuit, which is a highly stable source of spectral lines and a specialized power supply unit. The results of the experimental study along with metrological analysis are presented. The proposed technical solution in terms of developing a stable source of spectral lines made it possible to obtain a high level of both short-term and long-term stability of the spectral lines.

The emission spectroscopy of the [formula omitted] system of the CD radical

The emission spectrum of the 0-0,1-1 and 2-2 bands of the C2Σ+-X2Π system in the CD molecule have been obtained using a stainless steel hollow-cathode lamp with two anodes and filled with a mixture of He buffer gas and CD4. The emission from the discharge was observed with high accuracy dispersive optical spectroscopy using a plane-grating spectrograph and recorded by a photomultiplier tube. In total, 428 transition frequencies belonging to the three bands were precisely measured and rotationally analyzed. The current data were elaborated with the help of precise ro-vibrational and equilibrium ground state parameters reported by Zachwieja et al. (2012) from investigation of the A2Δ-X2Π transition. The spin-rotation interaction constants γv and γD,v of the C2Σ+,v=0,1,2 levels were obtained for the first time. Moreover, the main equilibrium parameters of the third excited state were obtained as follows: Te=31,825.944(12) cm−1, ωe=2078.803(27) cm−1, ωexe=59.558(12) cm−1, Be=7.86810(23) cm−1, αe=0.25315(58) cm−1 and γe=-0.01518(28) cm−1.

Ultraviolet laser spectroscopy of aluminum atoms in hollow-cathode lamp

We report on the precision measurement of aluminum atoms transition at 394 nm and transition at 396 nm in a hollow-cathode lamp. Both absorption and saturated absorption spectra are measured. From the absorption spectra, the Doppler linewidth is estimated to be 2.65 GHz. The saturated absorption spectra are analyzed based on a velocity-changing collisions model. With a frequency comb calibrated wavemeter, the frequencies of transition and transition are measured to be 759.905 204(1) THz and 756.547 133(3) THz, respectively. The hyperfine coupling constants of aluminum atoms are determined, and are compared with previously reported measurement results and theoretical calculation results. Reasonable agreement is found for the magnetic dipole constant (A constant), while the electric quadrupole constant (B constant) has a large deviation.

Sensitive and Accurate Determination of Cobalt at Trace Levels by Slotted Quartz Tube-Flame Atomic Absorption Spectrometry Following Preconcentration with Dispersive Liquid–Liquid Microextraction

Slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS) was used as a sensitive technique for the determination of cobalt, an element has toxic effects on living organisms at high doses. For the preliminary preconcentration of cobalt prior to the analysis, dispersive liquid–liquid microextraction (DLLME) was used. The instrument is equipped with a SQT to further increase the sensitivity by increasing the residence time of cobalt atoms in the light path emitted by a hollow cathode lamp. In the complex formation step, pH, the volume of buffer solution, the concentration of 1,5-diphenylcarbazone, and the volume of ligand were optimized. In addition, all of the system parameters, including the type and volume of the extraction solvent, dispersant type and volume of solvent, type of salt and the volume for the dispersion liquid–liquid microextraction, were optimized to obtain the lowest detection limit. Under the optimum conditions, the detection power of FAAS was improved by a factor of 86.56 fold using DLLME-SQT-FAAS. The limit of detection for the DLLME-SQT-FAAS system was 0.97 µg L−1. The applicability of the developed method was verified in tap and waste water samples by spiking measurements. The percentage recovery values for these were determined to be 91.7% and 111.0%, respectively.

Fourier transform emission spectroscopy and ab initio calculations on the visible spectrum of AlD[formula omitted

The spectrum of the AlD+ isotopologue has been investigated at high resolution in the 27,000−29,000 cm−1 region using a Fourier transform emission spectroscopy technique. The AlD+ molecules were produced within a water-cooled aluminum hollow-cathode lamp in the presence of 1.5 Torr of Ne and 0.8 Torr of ND3. The (0, 0) and (1, 1) bands belonging to the A2Π−X2Σ+system were recorded with an instrumental resolution of 0.03 cm−1. In total, almost 500 rotational frequencies were measured with an absolute accuracy of about 0.005 cm−1. It improved the experimental accuracy of the determined frequencies by the factor 10 compared to the previous work [J Phys B: Mol Phys 1984;17:L861-L866]. The rotational analysis has shown irregularities in the Λ− doubling splitting of the A2Π v=0,1. Consequently, the A2Π state has been represented by the rotational term values, while the regular X2Σ+ state by the molecular constants. The causes of the irregularities were identified in the interaction between the A2Π and the B2Σ+ states, which lies about 3720 cm−1 above. Supporting ab initio quantum chemical calculations, including spin-orbit effects, reproduce the observed spectroscopic constants including the small energy splittings due to spin-rotation interactions (for 2Σ+ states) and Λ−doubling.

Comparing the emission spectra of U and Th hollow cathode lamps and a new U line list

Context. Thorium hollow cathode lamps (HCLs) are used as frequency calibrators for many high resolution astronomical spectrographs, some of which aim for Doppler precision at the 1 m s−1 level. Aims. We aim to determine the most suitable combination of elements (Th or U, Ar or Ne) for wavelength calibration of astronomical spectrographs, to characterize differences between similar HCLs, and to provide a new U line list. Methods. We record high resolution spectra of different HCLs using a Fourier transform spectrograph: (i) U–Ne, U–Ar, Th–Ne, and Th–Ar lamps in the spectral range from 500 to 1000 nm and U–Ne and U–Ar from 1000 to 1700 nm; (ii) we systematically compare the number of emission lines and the line intensity ratio for a set of 12 U–Ne HCLs; and (iii) we record a master spectrum of U–Ne to create a new U line list. Results. Uranium lamps show more lines suitable for calibration than Th lamps from 500 to 1000 nm. The filling gas of the lamps significantly affects their performance because Ar and Ne lines contaminate different spectral regions. We find differences (up to 88%) in the line intensity of U lines in different lamps from the same batch. We find 8239 isolated lines between 500 and 1700 nm that we attribute to U, 3379 of which were not contained in earlier line lists. Conclusions. We suggest using a combination of U–Ne and U–Ar lamps to wavelength-calibrate astronomical spectrographs up to 1 μm. From 1 to 1.7 μm, U–Ne shows better properties. The differences in line strength between different HCLs underline the importance of characterizing HCLs in the laboratory. The new 3379 U lines can significantly improve the radial velocity precision of astronomical spectrographs.

Experimental radiative lifetimes, branching fractions, transition probabilities and oscillator strengths of some levels in Au I

Radiative lifetimes of ten odd-parity levels in neutral gold were measured by time-resolved laser-induced fluorescence method, and six of them were reported for the first time. Branching fractions (BFs) of 15 lines for eight of these levels were determined by the emission spectrum of a hollow cathode lamp. The transition probabilities and oscillator strengths of these lines were derived by combining the BFs with lifetime values. The lifetime and oscillator strength results are in very good agreement with previous data.

Synthetic spectra of BeH, BeD and BeT for emission modeling in JET plasmas

A theoretical model for isotopologues of beryllium monohydride, BeH, BeD and BeT, A to X visible and X to X infrared rovibronic spectra is presented. The MARVEL procedure is used to compute empirical rovibronic energy levels for BeH, BeD and BeT, using experimental transition data for the X , A , and C states. The energy levels from these calculations are then used in the program Duo to produce a potential energy curve for the ground state, X , and to fit an improved potential energy curve for the first excited state, A , including a spin–orbit coupling term, a Λ-doubling state to state (A–X states) coupling term, and Born–Oppenheimer breakdown terms for both curves. These, along with a previously computed ab initio dipole curve for the X and A states are used to generate vibrational-rotational wavefunctions, transition energies and A-values. From the transition energies and Einstein coefficients, accurate assigned synthetic spectra for BeH and its isotopologues are obtained at given rotational and vibrational temperatures. The BeH spectrum is compared with a high resolution hollow-cathode lamp spectrum and the BeD spectrum with high resolution spectra from JET giving effective vibrational and rotational temperatures. Full A–X and X–X line lists are given for BeH, BeD and BeT and provided as supplementary data on the ExoMol website.

Selective photoionization of lithium isotopes in a hollow cathode lamp: a feasibility study for a laser ion source and detector.

Two-step selective photoionization of lithium isotopes is carried out in a hollow cathode (HC) discharge lamp using a nitrogen-laser-pumped homemade tunable dye laser (∼0.2 cm-1, 7ns, 640-680nm). The HC lamp is developed in-house and used as a lithium ion source as well as a detector. The dark space region of HC discharge is illuminated by a dye laser exciting pulse followed by an ionizing radiation from the nitrogen laser. The high electric field (∼kV/cm) present in HC dark space is exploited for fast charge collection, produced by the simultaneous interaction of exciting and ionizing laser beams with sputtered lithium atoms, enabling the detection of photoionization signal. Photoionization signals with a high signal-to-noise ratio are obtained without using any amplifier. Effects of the ionizing laser pulse energy and the precise tuning of the dye laser on lithium photoionization signal, across 670.780nm (S1/22→P1/2,3/22) transition, are studied. The fine structure of lithium is clearly identified, and its two isotopes (Li7,6) are fairly resolved in the measured photoionization spectrum. Using a saturation technique, the photoionization cross section and the number density of lithium atoms for the Li7 (P3/22) excited level are also measured as 18.5±2.4 Mb, N0∼1.7×109 (atoms/cm3). The results obtained infer that HC-lamp-based photoionization is an easier and cost-effective way of selective photoionization of lithium atoms, and it can be applied for other elements also.

A frequency-stabilized light source at 399 nm using an Yb hollow-cathode lamp

We demonstrate a diode laser system operating at 399 nm that is stabilized to the 6s2 1S0–6s6p 1P1 electric dipole transition in ytterbium (Yb) atoms in a hollow-cathode lamp. The frequency stability of the laser reached 1.1 × 10−11 at an averaging time of τ = 1 s. We performed an absolute frequency measurement using an optical frequency comb and determined that the absolute frequency of the laser stabilized to the 1S0–1P1 transition in 174Yb was 751 526 522.26(9) MHz. We also investigated several systematic frequency shifts while changing some of the light source parameters and measured several isotope shifts. The measured laser frequency will provide useful information regarding the practical use of the frequency-stabilized light source at 399 nm.

Effect of ultrasonic field on the enzyme activities and ion balance of potential pathogen Saccharomyces cerevisiae

ObjectivesThis study aimed at investigating the enzyme activities and ion concentrations in potential pathogen S.cerevisiae upon ultrasonic treatment. MethodsThe activities of ATPase and antioxidase were identified by ATPase, SOD, and CAT assay kits following the instructions. Extracellular Ca2+ and K+ concentrations were determined in an atomic absorption spectrometer with calcium and potassium hollow-cathode lamps as radiation sources. ResultsSOD and CAT activities were enhanced by relatively low ultrasonic power at early time points and reduced to lower levels. Total ATPase, Na+/K+-ATPase, and Ca2+/Mg2+-ATPase activities were reduced by ultrasonic field, with higher reducing rate at stronger ultrasonic power and early time points. In addition, ultrasonic field disturbed the Ca2+ and K+ balances in S.cerevisiae cells. ConclusionsUltrasonic field resulted in the reduce even the lost of S.cerevisiae cell viability.

Experimental radiative lifetimes, branching fractions, and oscillator strengths of some levels in Tm III

Natural radiative lifetimes for five even-parity levels of Tm III were measured by time-resolved laser-induced fluorescence method. The branching fraction measurements were performed based on the emission spectra of a hollow cathode lamp. By combining the measured branching fractions and the lifetime values reported in this work and in literature, experimental transition probabilities and oscillator strengths for 11 transitions were derived for the first time.

Doppler-free spectroscopy of metastable Sr atoms using a hollow cathode lamp.

We report on the demonstration of Doppler-free spectroscopy of metastable Sr atoms using a hollow cathode lamp (HCL). We employed a custom Sr HCL, which is filled with a mixture of 0.5 Torr Ne and 0.5 Torr Xe as a buffer gas to suppress velocity changing collisions and increase the populations in all of the (5s5p)3PJ(J=0,1,2) metastable states. We performed frequency modulation spectroscopy for the (5s5p)3P0-(5s6s)3S1, (5s5p)3P1-(5s6s)3S1, (5s5p)3P2-(5s5d)3D2, and (5s5p)3P2-(5s5d)3D3 transitions with sufficient signal-to-noise ratios for laser frequency stabilization. We also observed the hyperfine transitions of (5s5p)3P2-(5s5d)3D3 of Sr87. This method would greatly facilitate laser cooling of Sr.

Polarization spectroscopy of atomic erbium in a hollow cathode lamp

In this work we perform polarization spectroscopy of erbium atoms in a hollow cathode lamp (HCL). We review the theory behind Doppler-free polarization spectroscopy, theoretically model the expected erbium polarization spectra, and compare the numerically calculated spectra to our experimental data. We further analyze the dependence of the measured spectra on the HCL current and the peak intensities of our pump and probe lasers to determine conditions. Applications include wavelength stabilization of diode laser radiation to the 400.91 nm erbium transition.

Excited-state population distributions of alkaline-earth metal in a hollow cathode lamp

The intensities of fluorescence spectral lines of Ca atoms and Sr atoms in two different hollow cathode lamps (HCLs) are measured by element-balance-detection technology. In the wavelength range of 350–750 nm in the visible spectral region, using the individual strongest line (Ca 422.67 nm, Sr 460.73 nm) as the bench mark, the population ratios between the excited states of Ca atoms and Sr atoms are calculated by rate equations and the spontaneous transition probabilities. The HCLs with populations at excited states can be used to realize the frequency stabilization reference of the laser frequency standard.

A UV digital micromirror spectrometer for dispersive AFS: spectral interference in simultaneous determination of Se and Pb

Hollow cathode lamps (HCLs) are excitation light sources commonly used in hydride generation atomic fluorescence spectrometry (HG-AFS).

Experimental radiative lifetimes, branching fractions, and oscillator strengths of some levels in Co i

The radiative lifetime measurements by the time-resolved laser-induced fluorescence technique are reported for 24 levels of Co i with the energy range of 283 45.86–55 922.3 cm−1, amongst which the lifetimes of 20 levels are reported for the first time. The branching fraction measurements by the emission spectrum of a hollow cathode lamp were performed for 11 levels of them together with other two levels reported in the literature, and branching fractions of 39 transitions were obtained. By combining them with lifetime values, the transition probabilities and absolute oscillator strengths of these lines were determined.

Comparison of three optical diagnostic techniques for the measurement of boron atom density in a H2/B2H6 microwave plasma

Three different optical diagnostic techniques have been used to measure the density of boron atoms in a microwave generated H2/B2H6 plasma of a diamond deposition reactor. These techniques are: optical emission intensity ratio of doublet 249.677 and 249.772 nm boron lines (OEIRD), laser induced fluorescence on 208.96 nm line (LIF) and resonance absorption on 249.772 nm line (RA) with a boron hollow cathode lamp (HCL) as light source. LIF results point to an important variation of the boron atom density with the distance from the substrate, in contradiction with OEIRD which indicates an almost constant density. RA measurements show a stronger absorption when the probe light from the HCL crosses the reactor outside the bright plasma core region than when it goes through the plasma core. This indicates a larger boron atom density in the volume surrounding the plasma core than inside it. As the plasma is not homogeneous, in the sense that the plasma induced emission is confined inside the plasma core but the ground state boron atoms are also present outside this region, the OEIRD method cannot be applied to this plasma. These experimental results question the simulation results of H2/B2H6 microwave plasma which predicted a fast decay of the boron atom density outside the plasma core.

Development of a see-through hollow cathode discharge lamp for (Li/Ne) optogalvanic studies.

Development of a demountable and see-through hollow cathode (HC) discharge lamp suitable for optogalvanic (OG) spectroscopy is described. The design of the HC lamp is simple, compact, and inexpensive. Lithium, investigated rarely by the OG method, is selected for cathode material as its isotopes are important for nuclear industry. The HC lamp is characterized electrically and optically for discharge oscillations free OG effect. Strong OG signals of lithium as well as neon (as buffer gas) are produced precisely upon copper vapor laser pumped tunable dye laser irradiation. The HC lamp is capable of generating a clean OG resonance spectrum in the available dye laser wavelength scanning range (627.5-676 nm) obtained with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye. About 28 resonant OG lines are explicitly observed. Majority of them have been identified using j-l coupling scheme and assigned to the well-known neon transitions. One line that corresponds to wavelength near about 670.80 nm is assigned to lithium and resolved for its fine (2S1/2 → 2P1/2, 3/2) transitions. These OG transitions allow 0.33 cm-1 accuracy and can be used to supplement the OG transition data available from other sources to calibrate the wavelength of a scanning dye laser with precision at atomic levels.