Hollow Cathode Lamp Research Articles

Broadband cavity-enhanced optical flux monitoring

This work describes a new type of sensor for growth process monitoring named broadband cavity-enhanced optical flux monitoring sensor (BBCE-OFM). Like existing optical flux monitoring (OFM) solutions, it relies on absorption spectroscopy. However, the implementation of an optical cavity reduces the measurement uncertainty, enabling efficient operation even at very low growth rates. Using the BBCE-OFM sensor mounted in our solid-source oxide molecular beam epitaxy reactor, we achieved an uncertainty of ±2% on the measurement of Sr and Ti growth rates in SrTiO3 at around 1 Ml/min, to be compared to the ±16% obtained in the same conditions using a conventional OFM setup. Furthermore, our sensor architecture, based on an echelle monochromator and LEDs replacing the hollow cathode lamps used in standard OFM sensors, is more robust against drift.

Accurate calibration spectra for precision radial velocities

Astronomical spectrographs require calibration of their dispersion relation, for which external sources like hollow-cathode lamps or absorption-gas cells are useful. Laser frequency combs (LFCs) are often regarded as ideal calibrators because they provide the highest accuracy and dense sampling, but LFCs are facing operational challenges such as generating blue visual light or tunable offset frequencies. As an example of an external source, we aim to provide a precise and accurate frequency solution for the spectrum of molecular iodine absorption by referencing to an LFC that does not cover the same frequency range. We used a Fourier Transform Spectrometer (FTS) to produce a consistent frequency scale for the combined spectrum from an iodine absorption cell at 5200– 6200 Å and an LFC at 8200 Å. We used 17 807 comb lines to determine the FTS frequency offset and compared the calibrated iodine spectrum to a synthetic spectrum computed from a molecular potential model. In a single scan, the frequency offset was determined from the comb spectrum with an uncertainty of ∼1 cms−1. The distribution of comb line frequencies is consistent with no deviation from linearity. The iodine observation matches the model with an offset of smaller than the model uncertainties of ∼1 m s−1, which confirms that the FTS zero point is valid outside the range covered by the LFC, and that the frequencies of the iodine absorption model are accurate. We also report small systematic effects regarding the iodine model’s energy scale. We conclude that Fourier Transform Spectrometry can transfer LFC accuracy into frequency ranges not originally covered by the comb. This allows us to assign accurate frequency scales to the spectra of customized wavelength calibrators. The calibrators can be optimized for individual spectrograph designs regarding resolution and spectral bandwidth, and requirements on their long-term stability are relaxed because FTS monitoring can be performed during operation. This provides flexibility for the design and operation of calibration sources for high-precision Doppler experiments.

The A2Π–X2Σ+ Band System of YO

YO bands are conspicuous in the spectra of S stars. The laboratory spectrum of the A2Π–X2Σ+ electronic transition has been recorded with a Fourier transform spectrometer using a composite-wall hollow cathode lamp source. The A2Π–X2Σ+ transition with v′≤4 and v″ ≤ 4 has been rotationally analyzed using the modern spectral fitting program PGOPHER. Vibronic band strengths were calculated using an ab initio transition dipole moment function. A line list for the A2Π–X2Σ+ transition is provided and can be utilized in the modeling of S stars.

Reflectivity measurement of a silicon carbide mirror sample for ITER divertor vacuum ultraviolet spectrometer.

The first mirror is the front-end optic component that reflects light emitted from the plasma to the diagnostic system in fusion plasmas. Silicon carbide (SiC), known for its relatively high mechanical strength and radiation tolerance, has been selected as the substrate material for the first mirror in the ITER divertor vacuum ultraviolet (VUV) spectrometer. To measure the reflectivity of the ellipse cylindrical SiC mirror to be manufactured, a device for reflectivity measurement in the VUV wavelength range was developed. First, the reflectivity of a sample SiC mirror (15mm diameter × 10mm thick) was measured across the ITER-required incidence angles, and the results are reported in this study. A hollow cathode lamp with helium gas was used as the VUV light source in the wavelength range of 23-60nm, and a dedicated VUV spectrometer to select specific wavelengths was developed. The spectrometer utilized laminar-type replica diffraction gratings (Shimadzu 30-006) and two back-illuminated charge-coupled devices (BI-CCD, Andor DO 940P-BEN) for the grating and detector, respectively. A cropping technique with aperture was employed to precisely localize the VUV light's reflection onto the SiC mirror surface. The experimentally measured reflectivity values of SiC at the required incidence angles of VUV light were compared with theoretically calculated reflectivity curves. The oxidation layer (SiO2) formed on the SiC surface and the incidence angle of VUV light to the BI-CCD chip (E2V) would be the factors affecting the accuracy of the reflectivity.

Cross-dispersion spectrograph calibration using only a laser frequency comb.

High-resolution cross-dispersion spectrographs are widely used in spectroscopy, but the two-dimensional format of the spectrum requires sophisticated calibration, conventionally performed by illuminating the instrument with a broadband hollow-cathode lamp and cross-referencing the result to an emission-line atlas. Here, we introduce a new technique to completely calibrate a high-resolution echelle spectrograph using only a laser frequency comb. Selected individual comb lines are removed from a broadband 20 GHz laser frequency comb-revealing their exact location in the spectrograph echellogram-and wavelength-tagged with sub-fm accuracy. In a complementary procedure, the comb is reduced to contain one line per echellogram order, enabling the spectrograph's free spectral range to be visualized and the exact concatenation between orders to be determined. In this way, the complete calibration of the high-resolution spectrograph is achieved using only a laser frequency comb, directly providing GPS-referenced accuracy without the need to bootstrap the calibration by indexing the comb modes using a broadband atomic-line source.

Characterisation of a hollow-cathode lamp to measure accurate branching fractions of rare-earth elements.

This work describes the tests performed with a newly built hollow-cathode lamp to ensure its capability to measure atomic parameters such as transition probabilities accurately. We discuss the design of the lamp and the experimental setup that will be used to measure transition probabilities. We show the discharge characteristics of the lamp and also the stability of spectral emission of the lamp over a period of two hours. Finally, it is concluded that the experimental setup, the lamp, and a camera with high resolving power are well suited for the measurement of the transition probabilities of doubly ionised rare-earths like Nd III.Graphical abstractGraphical abstract illustrating the use of a hollow-cathode lamp setup for accurately measuring branching fractions of rare-earth elements. The setup includes a diffraction grating spectrometer and a CMOS camera to detect radiation across a spectral range of 200 nm to 800 nm with a resolving power of 150,000 at 450 nm

New energy levels of atomic holmium discovered by laser spectroscopy in the near infrared spectral range

A combination of optogalvanic spectroscopy and laser-induced fluorescence spectroscopy with a continuous wave tunable single mode Ti-Sa laser was applied to find new energy levels of atomic holmium. Free and excited holmium atoms were produced in a liquid nitrogen-cooled hollow-cathode lamp. In this study, we examined 35 spectral lines of Ho I in the near-infrared wavelength range from 698 nm to 833 nm. Altogether, 16 new energy levels have been discovered, 5 levels of even parity and 11 levels of odd parity. Another four energy levels have been discovered but have already been published by another research group. Data on the hyperfine structure for the new levels are presented. Additionally, hyperfine structure data of three known levels of even parity were determined for the first time. The existence of the new energy levels was confirmed by analyzing 60 lines of previously measured Fourier transform spectra to precisely determine the energy of the levels.

Human health risk assessment model associated with PM2.5 bound metals in paradip port township, India

This study aimed to assess the environmental risk and human health risks associated with PM2.5-bound metals in Paradip city between January 2019 and December 2021. The seasonal average concentrations of PM2.5 were measured 91.43 ± 70.18 μg m−3, 103.40 ± 60.80 μg m−3, 124.74 ± 62.37 μg m−3, and 159.37 ± 77.88 μg m−3 in pre-monsoon, monsoon, post-monsoon, and winter season respectively. The highest and lowest concentrations are estimated in the winter and pre-monsoon season. Paradip city experienced tropical weather conditions with a hot and humid climate. The wind pattern shows that the predominant wind direction was observed from the south-south-west (SSW) direction. The metals in PM2.5 were analysed using an atomic absorption spectrophotometer (AAS) by air-acetylene flame using a hollow cathode lamp. The average metal concentration decreased in the order of Fe > Al > Zn > Pb > Cr > Mn > Ni > Cu > Co > Cd > As. The value of the geo-accumulation index (Igeo) was evaluated >1 for Cd, Fe, and Zn elements. The health risk assessment (HRA) results showed that non-carcinogenic risk (NCR) was higher through the inhalation route followed by ingestion and dermal contact. The cumulative NCR, which is expressed in terms of the hazard index (HI), is greater than 1 for infant (2.78E+00), child (2.53E+00), and adult (1.04E+00) via inhalation pathway. The total carcinogenic risk (TCR) for infants, children, and adults was estimated at 1.45E-04, 7.24E-05 and 1.25E-05, respectively, which exceeded the acceptable limit of 1.00E-06. Our comprehensive research plays an important role in both policymakers and relevant stakeholders for the preparation of city action plans concerning ambient air pollution, which can improve the air quality in and around Paradip city, India.

The PRL 2.5m Telescope and its First Light Instruments: FOC and PARAS-2

We present here the information on the design and performance of the recently commissioned 2.5-meter telescope at the PRL Mount Abu Observatory, located at Gurushikhar, Mount Abu, India. The telescope has been successfully installed at the site, and the Site Acceptance Test (SAT) was completed in October 2022. It is a highly advanced telescope in India, featuring the Ritchey-Chrétien optical configuration with primary mirror active optics, tip-tilt on sideport, and wave front correction sensors. Along with the telescope, its two first light instruments namely Faint Object Camera (FOC) and PARAS-2 were also integrated and attached with it in the June 2022. FOC is a camera that uses a 4096 X 4112 pixels detector SDSS type filters with enhanced transmission and known as u’, g’, r’, i’, z’. It has a limiting magnitude of 21 mag for 10 minutes exposure in the r’-band. The other first light instrument, PARAS-2, is a state-of-the-art high-resolution fiber-fed spectrograph operating in the 380-690 nm wave-band, aimed to unveil the super-Earth like worlds. The spectrograph works at a resolution of ∼107,000, making it the highest-resolution spectrograph in Asia to date, It is employed in an ultra-stable temperature and pressure environment, at 22.5 ± 0.001 ◦C and 0.005 ± 0.0005 mbar, respectively. Initial calibration tests of the spectrograph using a Uranium Argon Hollow Cathode Lamp (UAr HCL) have yielded intrinsic instrumental RV stability down to 30 cm s−1.

Branching Fractions and Transition Probabilities for UV Transitions in the Spectrum of Cr ii

We present transition probabilities for 268 spectral lines of singly ionized chromium (Cr ii) in the wavelength region 208–414 nm. Branching fractions were measured in archival Fourier transform spectra of chromium-argon and chromium-neon hollow cathode lamps and a Penning discharge source. The branching fractions were combined with previously published experimental lifetimes of 14 levels, and with lifetimes from semiempirical calculations for 14 levels to give transition probabilities. The estimated uncertainties of the transition probabilities range from 10% to 26%. A comparison with previously published experimental transition probabilities shows discrepancies of up to a factor of 2.5 for lines around 213 nm.

Experimental atomic data of spectral lines – I. Cs, Ba, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Re, and Os in the 370–1000 nm interval

ABSTRACT Atomic data are fundamental for plasma diagnostics in laboratory and astrophysics through spectroscopy. These data are extensively present in data bases for light elements, however incomplete for high-mass atoms. This paper presents the results of systematic spectroscopy of 17 elements with high Z, expected to be produced in kilonova events generated by neutron star mergers, whose spectral lines are not yet fully identified in stellar spectra and fusion devices. Experimental data are from échelle high-resolution (λ/Δλ = 60 000) spectroscopy of hollow cathode lamps obtained with the Catania Astrophysical Observatory Spectropolarimeter covering the 3700–10 000 Å range in a single exposure. A total of about 7700 spectral lines with energy level classification not previously listed in the NIST, Kurucz, and VALD data bases are here reported for neutral and singly ionized atomic transitions. For the spectral lines of any species, we report the measured wavelengths and their relative intensities. If possible, we also estimate the transition probabilities under the assumptions of optically thin emission and electric-dipole transitions. These are converted into oscillator strengths ready to be inserted in astrophysical data bases for spectral synthesis.

Experimental branching fractions, transition probabilities, and oscillator strengths of La I

Abstract Experimental branching fractions of 65 lines in La I were measured based on grating spectroscopy of a lanthanum hollow cathode lamp. Combining these branching fractions with previous energy lifetimes measured using time-resolved laser-induced fluorescence (TR-LIF) spectroscopy, absolute transition probabilities and oscillator strengths were determined for 34 lines belonging to transitions 4f5d6s–5d6s2, 4f5d6s–5d3, 5d26p–5d6s2, 5d27p–5d26s and for 31 lines associated with uncertain configurations due to dramatic configuration interaction mixings. These fundamental atomic data will help make atomic models more realistic and provide useful parameters for future astrophysical spectral analysis.

DC/DC converter to power spectral lamps

Objectives. The paper describes the creation of a DC/DC converter for powering hollow cathode lamps widely used currently as highly stable sources of spectral lines in spectral absorption analyzers and other applications. Typically, mains power supplies are used for such lamps, since installations using hollow cathode lamps are manufactured as stationary. However, there are no principal obstacles to manufacturing portable versions by simply substituting the power supply. However, special attention should in this case be paid to the power supply of the spectral lamp itself, since the amplitude stability of the radiation depends on the smoothness of its supply voltage. Therefore, the development of the pulse DC/DC converter with high efficiency and low rippling is a relevant and expedient problem.Methods. The set task is solved by methods of mathematical calculations, circuit simulation in LTSpice XVII сomputer-aided design system, and experimental verification.Results. The structural and principal electrical circuit of a prototype converter is developed on the basis of a topological analysis of pulse DC/DC converters, along with its calculations and simulation, and a printed circuit board. The developed autonomous high-voltage DC/DC converter has a low ripple level (~250 mV) of the output voltage (~491 V) at a load current of ~20 mA to ensure highly stable radiation.Conclusions. The possibility of obtaining a high voltage when using the topology of a step-up DC/DC converter with a choke is demonstrated. The experimental verification confirmed the correctness of calculations and modeling of a high-voltage DC/DC converter for powering hollow cathode spectral lamps.

Impacts of Some Trace Metals in Cyprinus carpio (Linnaeus,1758) and Tor soro (Valenciennes, 1842) on Human Health.

Although fish are rich sources of various trace metals in their bodies, when these metals exceed health safety limits, it becomes a global concern. Fish exposed to trace metal pollution in their aquatic ecosystems can lead to bioaccumulation and transfer to consumers. Monitoring trace metal contamination of fish food is crucial because they can reach humans through the aquatic food chain, resulting in health problems. Therefore, a first attempt was made for the analysis of trace metals in two cyprinid fish species, namely Cyprinus carpio (Common carp) and Tor soro (Mahseer), which were abundantly found in Khanozai Dam and assessing their potential health impacts when consumed by humans. A total of 200 fish specimens were collected from this area. These specimens were divided equally between the two carp species, with 100 individuals from each species. The fish specimens were collected over 12months, from June 2020 to May 2021 to determine the concentration of some trace metals, i.e. Manganese (Mn), Calcium (Ca), Iron (Fe), Potassium (K), and Zinc (Zn), Sodium (Na), Phosphorus (P), Magnesium (Mg), and Chlorine (Cl) using a Flame Atomic Absorption Spectrophotometer with a multi-element hollow cathode lamp. The obtained results from the trace metal analysis of Cyprinus carpio and Tor soro in this study revealed that both calcium and phosphorus were present in higher concentrations. However, iron, manganese, and zinc were not detected in both species. Additionally, magnesium was also not detected in C. carpio. For Cyprinus carpio, the arrangement was Ca > P > K > Na > Cl, while for Tor soro, it was Ca > P > Na > K > Cl > Mg in decreasing order. The health risks associated with fish consumption were assessed using factors like estimated daily intake (EDI), Target Hazard Quotient (THQ), and Total Target Hazard Quotient (TTHQ). The THQ values for all analyzed trace metals in both carp species exceeded the maximum value of 1.0, except for Cl in Tor soro. This suggests the potential for various health-related diseases in regular consumers due to their elevated levels. In both species, the TTHQ factor also surpassed the standard value of 1.0, indicating an acute health risk for humans. Although EDI values did not surpass the recommended daily allowance (RDA), continuous consumption of these contaminated fish from this area could lead to severe health complications. Therefore, these results strongly indicated that the elevated levels of trace metals found in the highly abundant cyprinid species of Khanozai Dam could pose serious health-related issues for the local inhabitants.

Nozzle Electrode Point Discharge-Enhanced Oxidation and Portable Gas Phase Molecular Fluorescence Spectrometry for Sensitive Field Detection of Sulfide

It is still a challenge to accurately determine dissolved sulfide due to its susceptibility to contamination and loss during transportation, storage, and analysis in the laboratory, thus highlighting the necessity for its sensitive field analysis. Herein, a robust nozzle electrode point discharge (NEPD) enhanced oxidation coupling with chemical vapor generation (CVG) is described for the highly efficient and flameless conversion of sulfide (S2-) to SO2. Subsequently, a portable and low-power consumption gas phase molecular fluorescence spectrometry (GP-MFS) was constructed for the highly selective and sensitive determination of the generated SO2 via detecting its molecular fluorescence excited by a zinc hollow cathode lamp. Under optimal conditions, a limit of detection (LOD) of 0.1 μM was obtained for dissolved sulfide with a relative standard deviation (RSD, n = 11) of 2.6%. The accuracy and practicability of the proposed method were validated by the analyses of two certified reference materials (CRMs) and several river and lake water samples with satisfactory recoveries of 99%-107%. This work confirms that NEPD enhanced oxidation is a low energy consumption yet highly efficient method for the flameless oxidation of hydrogen sulfide and thus is suitable for the easy field detection of dissolved sulfide in environmental water by CVG-GP-MFS.

Comparison of bismuth atomic lamps for a non-dispersive atomic fluorescence spectrometry

The performance of two types of radiation sources – an electrodeless discharge lamp (EDL) and a boosted discharge hollow cathode lamp (Superlamp) – for atomic fluorescence spectrometry (AFS) was studied and compared using bismuth as a model analyte at 222.8 and 223.1 nm fluorescence lines. Hydride generation was used for analyte introduction to a miniature diffusion flame where the generated bismuthane was atomized. An in-house assembled non-dispersive atomic fluorescence spectrometer was adjusted so that either of the sources could be employed. The optimization of the radiation sources at chosen 40 Hz modulation rate included a duty cycle and applied currents (primary and boost), in addition to proper focusing on the flame atomizer. With optimum operation parameters the sensitivity achieved with the EDL was around an order of magnitude higher than that with the Superlamp, in agreement with the higher radiation intensity measured by an optical power meter and resulting limits of detection of 1.5 pg and 11 pg, for the EDL and the Superlamp, respectively.

Dysprosium optogalvanic spectroscopy in a hollow cathode lamp

This work presents data obtained from optogalvanic spectroscopy (OGS) of dysprosium (Dy) using a commercial hollow cathode lamp. Combining laser beams from two tunable dye lasers, it was possible to identify 13 electronic transitions from excited states of the atom not observed or registered in published papers and the NIST database; these lines were observed between 555–575 nm and 585–615 nm. The study of 13 two-step transitions found in this work complement the available data for the Dy which may support other research or any work using this atom.

Drift Performance and Chromatic Thermal Response of a Temperature Stabilized Solid-etalon Calibrator

Etalon-based calibrators have rapidly gained popularity over the past decade in the field of high-precision radial velocity and high-resolution spectroscopy studies. Solid etalons are compact, pressure insensitive, commercially available alternatives to customized air spaced Fabry–Perot etalons. For tight-budget projects and weight-constricted missions, calibration system built from solid etalon is an interesting option to explore. For those, achievable spectral stability becomes the biggest question due to increased thermal sensitivity of the cavity material. Here, the design and performance of a low-cost solid-etalon calibrator is presented. A dual-loop temperature control system keeps the temperature fluctuations to within 1 mK rms when fully stabilized. Drift performance was tracked simultaneously with a laser frequency comb and the chromatic thermal response is measured through temperature tuning. The results indicate that a thermally controlled solid-etalon system can demonstrate sufficient short-term stability (<1 m s−1) for precise wavelength calibration in combination with a hollow-cathode lamp, and the measured drift and chromatic thermal response agree with theoretical predictions. Such systems are plausible candidates for cost-effective calibration of m s−1 level precision radial velocity instruments with improvement in thermal isolation, optimization in data processing, and long-term testing in the foreseeable future.

Rapid, Simultaneous, and Automatic Determination of Lead and Cadmium in Cereals with a New High Performance Composite Hollow Cathode Lamp Coupled to Graphite Furnace Atomic Absorption Spectrometry

A simple, rapid, sensitive, accurate, and automatic graphite furnace atomic absorption spectrometry (GFAAS) method for detecting Cd and Pb in cereals is presented. This method enables the simultaneous determination of Cd and Pb in cereals with a pre-treatment method of diluted acid extraction and a high-performance lead-cadmium composite hollow-cathode lamp (LCC-HCL), and it realizes automatic determination from sample weighing to result output through an automatic diluted acid extraction system. Under the optimization, Pb and Cd in cereals were simultaneously and automatically detected in up to 240 measurements in 8 h. The LOD and LOQ of this method were 0.012 and 0.040 mg·kg-1 for Pb, and 0.0014 and 0.0047 mg·kg-1 for Cd, respectively. The results of the four certified reference materials were satisfied; there was no significant difference compared with the ICP-MS method according to a t-test, and the RSDs were less than 5% for Cd and Pb. The recoveries of naturally contaminated samples compared with the ICP-MS method were favorable, with 80-110% in eight laboratories. The developed method is rapid, low-cost, and highly automated and may be a good choice for grain quality discrimination and rapid analysis of Cd and Pb in different institutions.

Laser photo-ionization study of nat Ag using opto-galvanic signal at SPES offline laser lab

Resonant Ionization Laser Ion Source (RILIS) is one of the most advancing techniques for the production of radioactive ion beams (RIBs) in ISOL facilities. SPES project at INFN-LNL is a second generation ISOL facility which aims to produce several isotopes in a couple of years. Within the framework of this project, resonant photo-ionization schemes of several elements are studied in the offline laser lab, to be later implemented in the SPES Laser Ion Source. Silver is one of the elements being studied for the stated purpose. In this article, we report a resonant photo-ionization scheme of silver tested with a hollow cathode lamp (HCL). Evidence of high lying Rydberg states around 60945.32 cm−1 has also been observed by studying the fast opto-galvanic signal detected.