Hollow Cathode Lamp Research Articles

Dynamic-range extension of MAES multichannel analyzers based on BLPP-2000 and BLPP 4000 photodetector arrays

One trend in the development of integral atomic emission spectral analysis with low spectral background excitation sources, such as inductively coupled or microwave plasma, is to increase the dynamic range of spectrum recording systems based on photodetector arrays. To achieve low detection limits, it is necessary to use photodetector arrays with low reading noise. The dynamic range of a single readout of such photodetector arrays usually does not exceed four orders of magnitude. The dynamic range increase due to the accumulation of spectra from multiple acquisition leads to a quadratic increase in the measurement time. This method does not allow one to cover the entire dynamic range of spectral line intensities of inductively coupled or microwave plasma (which can reach seven orders of magnitude) while maintaining an acceptable total measurement time of a sample spectrum. As an alternative, it is proposed to increase the dynamic range toward higher line intensities by using two different alternating accumulation times during measurement. The objective of this study is to implement the proposed recording mode in MAES analyzers based on BLPP-2000 and BLPP-4000 photodetector arrays in order to increase the dynamic range of recorded spectral lines. Dependences of the signal-to-noise ratio and the dynamic range of spectral lines recorded in integral atomic emission spectrometry on the accumulation time, the total measurement time, the spectral background level, and the photodetector array parameters are obtained. It is shown theoretically that the use of the recording mode with alternating different accumulation times should increase the dynamic range of BLPP-2000 and BLPP-4000 photodetector arrays by two orders of magnitude. The dynamic range of spectral line intensities of a hollow-cathode lamp is shown experimentally to increase by two orders of magnitude (to five orders of magnitude).

Reference wavelengths of Si ii, C ii, Fe i, and Ni ii for quasar absorption spectroscopy.

Wavelengths of absorption lines in the spectra of galaxies along the line of sight to distant quasars can be used to probe the variablility of the fine structure constant, α, at high redshifts, provided that the laboratory wavelengths are known to better than 6 parts in 108, corresponding to a radial velocity of ≈20 ms-1. For several lines of Si ii, C ii, Fe i, and Ni ii, previously published wavelengths are inadequate for this purpose. Improved wavelengths for these lines were derived by re-analysing archival Fourier transform (FT) spectra of iron hollow cathode lamps (HCL), a silicon carbide Penning discharge lamp, and with new spectra of nickel HCLs. By reoptimizing the energy levels of Fe i, the absolute uncertainty of 13 resonance lines has been reduced by over a factor of 2. A similar analysis for Si ii gives improved values for 45 lines with wavelength uncertainties over an order of magnitude scer than previous measurements. Improved wavelengths for eight lines of Ni ii were measured and Ritz wavelengths from optimized energy levels determined for an additional three lines at shorter wavelengths. Three lines of C ii near 135 nm were observed using FT spectroscopy and the wavelengths confirm previous measurements.

Transient Double-Beam Spectrograph for the 2.5-m Telescope of the Caucasus Mountain Observatory of SAI MSU

The Transient Double-beam Spectrograph (TDS) is designed for optical low-resolution observations of non-stationary and extragalactic sources with the 2.5-m telescope of Caucasus Mountain Observatory of the Sternberg Astronomical Institute. It operates simultaneously in a short-wavelength (360--577 nm, reciprocal dispersion 1.21 A/pixel, resolving power R=1300 with a 1 arcsec slit) and long-wavelength (567--746 nm, 0.87 A/pixel, R=2500) channels. The light is split by a dichroic mirror with a 50% transmission at 574 nm. In the "blue" channel, the automatic replacement of the grating by a grism with a double resolving power is possible. Two CCD-cameras use E2V 42-10 detectors cooled down to $-70^\circ$C with a readout noise of 3 $e-$ at a readout rate of 50 kHz. The spectrograph is equipped with a back slit viewer camera and a calibration unit allowing to record a comparison spectrum from a hollow cathode lamp for wavelength calibration or from an LED source with a continuous spectrum (the "flat field") to take into account the vignetting and uneven slit illumination. The throughput of the entire optical path without slit loss is 20% at the zenith in the "blue" and 35% in the "red" channel. Excluding the atmosphere and the telescope, the efficiency of the TDS itself reaches a maximum of 47% and 65% respectively. The spectrograph is permanently mounted in the Cassegrain focus of the 2.5-m telescope of CMO SAI MSU sharing the port with a wide-field photometric CCD-camera. The spectrograph is fed by the light from a folding mirror introduced into the optical path. Since November 2019, TDS has been used for regular observations of non-stationary stars and extragalactic sources up to 20-th mag in a 2-h exposure with a signal-to-noise ratio >5 per pixel.

A Faraday Anomalous Dispersion Optical Filter Based on Rubidium Hollow-Cathode Lamp

Using a hollow-cathode lamp (HCL) to build a Faraday anomalous dispersion optical filter (FADOF) is a new method to realize narrow linewidth optical filters. In contrast to other atomic optical filters based on saturated vapors, which work at a relatively high temperature to maintain the atomic density, the HCL device using sputtered particles can work at a much lower temperature. In this work, a rubidium HCL-based FADOF (HCL-FADOF) working at 780 nm is established and carefully tested. With 20 mm cathode length, the transmittance can reach 29% under 18 mA discharge current and 260 G magnetic field at room temperature, which is equivalent to the performance of a saturated vapor-based FADOF (VC-FADOF) at more than 60 ∘C. This work provides a direct comparison of the performance of the HCL-FADOF and the VC-FADOF, which is of great benefit to further studies of atomic filters at normal temperature.

Laser spectroscopy of metastable palladium at 340 and 363 nm

We report measurements of the isotope shift of the mass 104, 105, 106, 108, and 110 stable palladium isotopes for transitions from the metastable state $4{d}^{9}{(}^{2}{D}_{5/2})5s,{\phantom{\rule{0.16em}{0ex}}}^{2}{[5/2]}_{3}\ensuremath{\rightarrow}4{d}^{9}{(}^{2}{D}_{5/2})5p,{\phantom{\rule{0.16em}{0ex}}}^{2}{[7/2]}_{4}^{o}$ at 340 nm, and $4{d}^{9}{(}^{2}{D}_{5/2})5s,{\phantom{\rule{0.16em}{0ex}}}^{2}{[5/2]}_{3}\ensuremath{\rightarrow}4{d}^{9}{(}^{2}{D}_{5/2})5p,{\phantom{\rule{0.16em}{0ex}}}^{2}{[3/2]}_{2}^{o}$ at 363 nm. For $^{105}\mathrm{Pd}$, we determine the hyperfine structure of both transitions. The measurements were performed by saturation absorption spectroscopy in a custom-built hollow cathode lamp and will serve as a reference for collinear laser spectroscopy of short-lived neutron-rich palladium isotopes. We also report on the observation of a population inversion for the 363-nm transition under certain discharge conditions.

Observations of Radial Velocity Variability in Stars from the Spectra Obtained with the BTA Fiber-Fed Spectrograph in High Spectral Resolution Mode

Abstract—We present the results of observations of radial velocity variability in stars with exoplanets. Observations of a number of stars with characteristic stellar magnitudes from 8.54m to 10.5m were carried out using a new high-resolution (R = 35 000–120 000) fiber-fed spectrograph mounted at the foundation of the 6-m BTA telescope, in the mode of resolutions from R = 45 000 to R = 65 000 with a simultaneous registration of the calibration spectrum of a thorium–argon hollow cathode lamp. The achieved characteristic measurement accuracies ranged from a few to several tens of m s−1. In the future, the thorium-argon lamp will be supplemented with a Fabri–Perot etalon to reach the radial velocity measurement accuracy in stars up to 1 m s−1.

Dual-beam potassium Voigt filter for atomic line imaging.

Spectrally narrowband imaging in remote sensing applications can be advantageous for detecting atomic emission features. This is especially useful in detecting specific constituents within rocket plumes, which are challenging to discern from naturally occurring sunglints. In this paper, we demonstrate a dual-beam technique, implemented with a Wollaston prism, for calibrating a Voigt magneto-optical filter for a linear polarizer's finite extinction ratio, as well as optical misalignment between the linear polarizers' transmission axes. Such a strategy would be key towards expanding the filter's field of view while maintaining its classification capabilities. Validation of the potassium Voigt filter is demonstrated using the simulation tool ElecSus in combination with a potassium hollow cathode lamp. RMS error between the filter's temperature response and that of the simulation was approximately 2%. We then demonstrate the detection of a potassium model rocket motor outdoors alongside a sunglint. Results indicate a 20-fold increase in contrast when using our dual-beam calibration strategy.

Characterization of ytterbium resonance lines at 649 nm with modulation-transfer spectroscopy

We report modulation-transfer spectroscopy (MTS) on the $6\mathit{s}6\mathit{p}\phantom{\rule{0.16em}{0ex}}^{3}P_{0}\ensuremath{\leftrightarrow}6\mathit{s}7\mathit{s}\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ transition in neutral ytterbium (Yb) isotopes in a hollow cathode lamp. The MTS dispersive signals show an effective linewidth of 70 MHz, contributed primarily by the pressure broadening. MTS has demonstrated the capability of completely resolving all isotopic lines, except the one in low-abundance $^{168}\mathrm{Yb}$. Frequency measurements of the isotope-stabilized laser are performed using an optical comb, and systematic shifts therein are corrected. We have examined the relative isotope shifts, and the hyperfine constants for the $6\mathit{s}7\mathit{s}\phantom{\rule{0.16em}{0ex}}^{3}S_{1}$ state are given as $\mathit{A}(^{171}\mathrm{Yb})=6837.83(19)$ MHz, $\mathit{A}(^{173}\mathrm{Yb})=\ensuremath{-}1891.46(7)$ MHz and $\mathit{B}(^{173}\mathrm{Yb})=\ensuremath{-}0.62(16)$ MHz. Our results are in reasonable agreement with previously reported values and essentially resolve the existing discrepancies.

New energy levels of atomic lanthanum with small total angular momentum quantum number discovered by laser spectroscopic methods in the near IR

Optogalvanic spectroscopy as well as laser-induced fluorescence spectroscopy were applied in order to find new energy levels of atomic lanthanum. A hollow-cathode lamp and a tuneable continuous wave titanium-sapphire laser in the wavelength range from 750 nm to 850 nm were used for the measurements. Three energy levels of even parity with small values of total angular momentum quantum number J were discovered: 38 519.18 cm−1with J=1/2,40 392.80 cm−1with J=3/2,and 42 191.24 cm−1with J=3/2. The existence of these three levels was confirmed by laser excitations of several spectral lines as well as by spectral lines from a Fourier transform spectrum. Magnetic dipole hyperfine structure constants of the three new levels were determined from fits of the experimental spectra of the laser lines.

Detection of Heavy metals in Fruits and Vegetables Available in the Market of Quetta City

This study is conducted for the determination of heavy metals concentration like Fe, Ni, Mn, Co, Cd, Cu and Pb in five edible vegetables (Cauliflower, Cabbage, Cucumber, Lady finger and Tomato), five edible Fruits (Water melon, peach, Banana, Mango (Sindhri & Langra) and apple) and peel of all these Fruits and endocarp of apple. Samples were purchased from the Local Market of Quetta city (Capital of Balochistan). Atomic Absorption Spectrophotometer ((FAAS, Thermo ­­­­­- Electron Corporation, S4 AA System, Ser. No, GE711544, China) double beam and deuterium background hollow cathode lamps of Fe, Pb, Cd, Co, Cu, Ni and Mn were used at specific wavelengths for the determination of heavy metals concentration. Samples were run three times and at least three or four standards are used for each metal analysis. Concentration of Fe, Mn, and copper were very much below the permissible limits defined by WHO/FAO. Concentration of Ni was found at toxic level in cucumber. Concentration of Cd was above the safe value in all samples except banana fruit given by WHO/FAO. Concentration of Co was found above the limit defined by ASTDR 1994 in all the samples. Concentration of Pb with respect to the (China food hygiene standards 1994) 0.2mg/kg and WHO/FAO 0.3mg/kg is above the limit in all samples but it found very high in Tomato, Cabbage, Cucumber, Peach and Watermelon. The overall result of this study reveals that the samples of vegetable and fruits are highly contaminated with heavy metals Co, Pb, Ni and Cd due to the usage of drainage water for watering them and their consumption can cause hazardous effect on human health.

A uranium atlas, from 365 to 505 nm

A Fourier-transform spectrum of the emission from a commercial uranium hollow-cathode lamp 19,800–27,400 cm−1 is proposed, in ascii format, as a possible aid to calibration of laser excitation spectra.

High-resolution continuum source atomic absorption spectrometry: a review of current applications

Atomic absorption spectrometry (AAS) is one of the most widely used and available methods for analysis of substances and materials. It allows one to determine about 70 elements from the periodic table and is characterized by rapidity, high accuracy and sensitivity, as well as simplicity of analytical techniques. A feature of AAS is simultaneous determination of only one element due to the use of a measurement design with a line source (hollow-cathode lamps, high-frequency electrodeless lamps, optical quantum generators, etc.). To make AAS more competitive, the first commercially available continuum source atomic absorption spectrometer was designed in 2004. Unique analytical capabilities of the new instruments found application first of all in the analysis of food, pharmaceuticals, waste and drinking water, oil and petrochemicals, biological objects, etc. This review covers publications on the application of continuum source AAS in analytical chemistry and provides a development outlook of the method.

Determination of palladium in soil samples by slotted quartz tube-flame atomic absorption spectrophotometry after vortex-assisted ligandless preconcentration with magnetic nanoparticle-based dispersive solid-phase microextraction.

In this study, a rapid and effective dispersive solid-phase microextraction (d-SPME) method was developed to preconcentrate Pd from aqueous extract of soil samples by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). The unique properties of magnetic nanoparticles (MNPs) were used to directly isolate Pd from the sample solutions without the need for complexation. Significant parameters of the extraction method such as magnetic nanoparticle type and amount, pH and amount of buffer solution, amount of eluent, and mixing type and period were optimized together with other instrumental parameters to boost the absorbance signal of Pd. An SQT was fitted onto the burner head to boost the interaction between Pd atoms and hollow cathode lamp radiation to enhance absorbance signals. The limit of detection (LOD) and limit of quantification (LOQ) values for Pd determined (d-SPME-MNP-SQT-FAAS) were 6.4 and 21.4ng/mL, respectively. The percentage relative standard deviation of the developed method was calculated as 6.6%. The method was applied to soil samples taken from the campus area and spiked recovery experiments were performed to evaluate the method's accuracy/applicability. Satisfactory percent recovery results (90-101%) were obtained for different spiked concentrations and this proved the accuracy/applicability of the method.

Chemical Interaction of InAs with Zinc

The partial pressure of Zn over the system including three condensed phases [(In-Zn)-InAs(s)-Zn3As2(s)] has been determined between 617 K and 740 K by optical absorption of a vapor phase at 307.6 nm using a Zn hollow cathode lamp as a source of radiation. The array of experimental data contained 52 values of Zn pressure from 0.32 Pa up to 20 Pa at different temperatures. Using this information the activity of zinc and its mole fraction in metal phase (from 4.6 at.% to 8.3 at.%) were founded. The dependences of ln p and $$ \ln K_{a}^{ \circ } $$ against reciprocal temperature for reaction: 1/3Zn3As2(s) + 2/3In(liquid) = Zn(g) + 2/3InAs(s) were approximated by linear functions. For considered temperature range the standard enthalpy of reaction was calculated as equal to 126 ± 1 kJ/mol.

ATOMIC ABSORPTION SPECTROPHOTOMETER – A VERSATILE TOOL FOR THE ESTIMATION OF NICKEL CONTENT IN DRONEDARONE

Objective: The present investigation is to develop a validated analytical method for the determination of nickel content in dronedarone hydrochloride bulk drug by atomic absorption spectrophotometer (AAS).
 Methods: Samples were analyzed after a preparation of sample solution by dissolving in suitable diluents of nitric acid and perchloric acid. In the present method, AAS with 0.2 nm slit width, nickel hollow cathode lamp with a wavelength of 232 nm has been employed.
 Results: The system suitability parameters were performed to assess the system performance. The limit of detection and limit of quantification (LOQ) were found to be 0.051 ppm and 0.15 ppm, respectively. The percentage recovery at LOQ, 50%, 100%, and 150% levels of nickel in dronedarone was found to be 95.55, 109.33, 96, and 97.55, respectively.
 Conclusion: With the developed method, the nickel content in dronedarone bulk sample was found to be 3.0 ppm.

Fourier-transform spectroscopy of the A2Πi − X2Σ+ system in CO+ and deperturbation analysis of the A2Πi(v = 0, 1) levels

The A2Πi state of 12C16O+ has been reinvestigated using high-resolution, emission spectra obtained via Fourier-transform spectroscopy of the (0, 1), (0, 2), (1, 0) and (1, 1) bands of the Comet–Tail (A2Πi − X2Σ+) system with accuracy of up to 0.005 cm−1. The high temperature (900 K) of the emission discharge inside the hollow-cathode lamp permitted monitoring of high rotational quantum levels in A2Πi(v = 0, 1) up to J = 48.5. All these bands together with the X2Σ+ − X2Σ+(10, 1) and (10, 2) transitions deriving from a complex, spin-orbit, spin-electronic and L-uncoupling A2Π(v = 0) ∼ X2Σ+(v = 10) interaction as well as the B2Σ+ − X2Σ+(6, 10) frequency transitions from our previous study were taken into consideration. In total, 1849 spectral lines were included in the comprehensive deperturbation analysis. This fit leads to a much improved description in terms of deperturbed molecular constants and interaction parameters compared to the previous studies of the same energy region in CO+. Moreover, the ro-vibronic term values of the A2Πi(v = 0) level and its perturber X2Σ+(v = 10) were determined as well as Λ-doubling of A2Πi(v = 0,1), γ-doubling of X2Σ+(v = 10) and percentage 2Π character of these levels were considered in detail.

Experimental radiative lifetimes, branching fractions, and oscillator strengths of Ta I levels

Radiative lifetimes for 20 levels of Ta I in the energy range of 30 664.66–43 550.78 cm−1 were measured by the time-resolved laser-induced fluorescence technique. Among the results, to our knowledge, 17 lifetimes are reported for the first time. These lifetime values are in the range from 8.5–97 ns. A good agreement is achieved between the present and previously reported results. Branching fractions (BFs) of 97 transitions related to 13 of these levels were determined from the emission spectra of hollow cathode lamps recorded by the Fourier transform spectrometer at the National Solar Observatory on Kitt Peak, USA, available from digital library (http://diglib.nso.edu/ftp.html). By combining these BFs with our lifetime results, absolute transition probabilities and oscillator strengths for these lines were obtained.

A Highly Stable Source of Spectral Lines

In spectroscopy, hollow cathode lamps are subject to increased requirements for radiation parameters. To check spectrometric equipment, it is necessary to create a highly stable source of spectral lines, the intensity of which on the given spectral lines will remain unchanged (≤1%) for a long time. A solution to this problem is proposed, and a scheme of an experimental test bench for a hollow cathode lamp with an optical-electronic negative feedback loop is presented. The feedback signal controls the current source, which is a functional unit of a specialized power supply unit and generates an electric current flowing through the lamp. The results of an experimental study with an appropriate metrological analysis are presented. The proposed technical solution to build a stable source of spectral lines allowed us to obtain a high level of stability of spectral lines in both the short and long term.

New wavelength calibration for echelle spectrographs using Fabry-Pérot etalons

Context. The study of Earth-mass extrasolar planets via the radial-velocity technique and the measurement of the potential cosmological variability of fundamental constants call for very-high-precision spectroscopy at the level of δλ/λ < 10−9. Only an accurate wavelength calibration of the spectrograph can guarantee that the aimed precision is achieved over a multi-exposure and multi-epoch data set. Wavelength accuracy is obtained by providing two fundamental ingredients: 1) an absolute and information-rich wavelength source and 2) the ability of the spectrograph and its data reduction of transferring the reference scale (wavelengths) to a measurement scale (detector pixels) in a repeatable manner. Aims. The goal of this work is to improve the wavelength calibration accuracy of the HARPS spectrograph by combining the absolute spectral reference provided by the emission lines of a thorium-argon hollow-cathode lamp (HCL) with the spectrally rich and precise spectral information of a Fabry-Pérot-based calibration source. Methods. On the basis of calibration frames acquired each night since the Fabry-Pérot etalon was installed on HARPS in 2011, we constructed a combined wavelength solution that fits simultaneously the thorium emission lines and the Fabry-Pérot lines. The combined fit was anchored to the absolute thorium wavelengths, which provide the “zero-point” of the spectrograph, while the Fabry-Pérot lines were used to improve the (spectrally) local precision. The obtained wavelength solution was verified for auto-consistency and tested against a solution obtained using the HARPS laser-frequency comb (LFC). Results. The combined thorium+Fabry-Pérot wavelength solution shows significantly better performances compared to the thorium-only calibration. In both cases, the residuals of the LFC line positions to the fitted wavelength solution follow a Gaussian distribution with an rms value of about 14 m s−1 for the combined solution, and twice as large for the thorium-only solution (29 m s−1). Given these positive results, we have applied the new calibrations to scientific frames and tested the radial-velocity residual on three well-known stars: HD 10700, HD 20794, and HD 69830. In all three cases the radial-velocity (RV) scatter could be reduced compared to the measurements using the previous calibration. Conclusions. The richness of the Fabry-Pérot spectrum helps to improve the wavelength calibration using thorium-argon lamps or extending the wavelength domain of LFCs with limited operational range. The presented techniques will therefore be used in the new HARPS and HARPS-N pipeline, and will be exported to the ESPRESSO spectrograph.

An atomic fluorescence spectrometer for monitoring nitrogen nutrients via NO vapor generation

Long-term and multipoint monitoring is very important to evaluate the safety of water environment. Atomic fluorescence spectrometer (AFS) is generally used for analyzing metals or metalloids in water quality monitoring. In the present work, for the first time, AFS is employed for sensitive monitoring of nitrogen nutrients, i.e., NO2−, NO3− and NH4+, with nitric oxide (NO) vapor generation. By taking advantage of the different vapor generation conditions for NO2−, NO3− and NH4+, a unit integrating with sampling, heating, cooling, gas-liquid separation and moisture removal is employed for controlling the vapor generation process, by reacting with either iodide or titanium (III). An antimony hollow cathode lamp is used for the excitation of NO to produce fluorescence emission at 193–320 nm. Linear calibration graphs are obtained within 0.02–2, 0.1–20, 0.2–1 mg L−1 for NO2−, NO3− and NH4+, along with detection limits of 0.006, 0.03, 0.06 mg L−1, respectively. The new analytical strategy obviously broadens the application of AFS, and it is well demonstrated by the determination of NO2−, NO3− and NH4+ in certified reference materials as well as various real water samples, providing competitive sensitivity with the current techniques for nutrient monitoring in environmental water.