Spectral line shape fitting in instrumental neutron activation analysis of pottery

The γ-ray spectrum of a neutron-activated clay standard is analyzed by spectral line shape fitting and the results are compared with an empirical analysis of the spectrum based on detector calibrations. It is concluded that trace element analysis of pottery may be simplified and enhanced by a combination of spectral line shape fitting and detector calibrations.     

Spectral interferences using the Zeeman effect for furnace atomic absorption spectroscopy

Using a transverse, a.c. Zeeman system, with the magnet on the analyte, background correction is performed at the exact analyte wavelength. As a result, nearly all of the spectral interferences associated with continuum correction are eliminated. Errors may occur, though, using Zeeman correction if coincident or nearby absorption lines or molecular absorption bands exhibit Zeeman splitting.We have found an example of overcorrection in the determination of Cd at the alternate 326.1-nm line that we believe is due to splitting of PO bands. We have also confirmed errors from Ft in the determination of Fe at the alternate 271.9-nm line and from Co in the determination of Hg at 253.6 nm.     

High-resolution laser spectroscopy of H2 in a fast beam

High-resolution laser photofragment spectroscopy is performed in a fast beam of H₂c³Π_u⁻ formed by near resonant charge exchange. The observed linewidths allow partial resolution of the fine and hyperfine structure in the 1s3d g ³Σ⁺_g Rydberg state. Simulations of the spectra indicate that the hyperfine splittings are very close to those of H⁺₂ as expected for Rydberg states.     

Optimization of detection of atomic absorption lines in intracavity laser spectroscopy

An intracavity laser spectrometer equipped with a graphite furnace electrothermal atomizer and two alternative types of narrow atomic lines detection schemes (high resolution diffraction spectrograph with optical multichannel analyzer or a resonant detector based on a hollow-cathode lamp) is described. Such system was used to determine ultra-trace amounts of lithium and strontium in aqueous solutions. A significant reduction in the measurable absorbance was demonstrated for both elements. Careful optimization of the operating conditions of the detection systems and a comparison of their typical features and advantages were performed.     

Optimization of detection of atomic absorption lines in intracavity laser spectroscopy

An intracavity laser spectrometer equipped with a graphite furnace electrothermal atomizer and two alternative types of narrow atomic lines detection schemes (high resolution diffraction spectrograph with optical multichannel analyzer or a resonant detector based on a hollow-cathode lamp) is described. Such system was used to determine ultra-trace amounts of lithium and strontium in aqueous solutions. A significant reduction in the measurable absorbance was demonstrated for both elements. Careful optimization of the operating conditions of the detection systems and a comparison of their typical features and advantages were performed.     

Simulating systematic errors in X-ray absorption spectroscopy experiments: Sample and beam effects

The article presents an analytical model to simulate experimental imperfections in the realization of an X-ray absorption spectroscopy experiment, performed in transmission or fluorescence mode. Distinction is made between sources of systematic errors on a time-scale basis, to select the more appropriate model for their handling. For short time-scale, statistical models are the most suited. For large time-scale, the model is developed for sample and beam imperfections: mainly sample inhomogeneity, sample self-absorption, beam achromaticity. The ability of this model to reproduce the effects of these imperfections is exemplified, and the model is validated on real samples. Various potential application fields of the model are then presented.     

Rubidium isotope measurements in solid samples by laser ablation-laser atomic absorption spectroscopy

Laser atomic absorption was used to measure the rubidium isotopes in a laser-induced plasma. An ⁸⁵Rb/⁸⁷Rb isotope ratio of 2.7±0.2 was determined in solid calcium carbonate samples. A Nd:YAG laser was used to produce the plasma on the surface of solid samples placed inside a low pressure chamber with a controlled atmosphere of 150 mtorr to 10 torr. The plasma conditions were optimized in order to provide the best sensitivity and resolution. A narrowband Ti:Sapphire laser was scanned across the 780.02-nm transition of the rubidium isotopes. The resolved isotope spectrum is shown, as well as the isotope selective calibration plots. A detection limit of 25 ppm for the individual isotopes was obtained. The optimization studies and the likely mechanisms of line broadening are discussed.     

Velocity control and cooling of an atomic beam using a modeless laser

A newly developed continuous wave broadband laser which lacks mode structure in the frequency domain is employed together with a single mode laser beam to decelerate and cool metastable neon atoms. The velocity of the atoms in the beam can be set to a desired velocity by tuning the frequency of the single mode laser.     

Spectral features of atomic magneto-optical rotation spectroscopy (the atomic Faraday effect) and Zeeman splittings of various elements

Spectral features of atomic magneto-optical rotation spectroscopy (AMORS) or the atomic Faraday effect of various elements are described. As a stable atomizer, an air-hydrogen flame is located between the pole pieces of the electromagnet. The dependence of the transmitted intensity on the magnetic field strength was recorded on an X-Y recorder by scanning the magnetic field. For most of the analytical lines of elements, the maximum energy was transmitted through the optical system in the Faraday configuration at magnetic field strengths of up to a few kilogauss. The theoretically calculated Zeeman splitting patterns are successfully related to the experimental results.     

A line profile study of the 193.76 nm arsenic emission line from lamps used in atomic absorption spectroscopy

The width of the 193.7 nm line of arsenic has been measured for a commercial hollow cathode lamp (HCL), a pumped hollow cathode lamp and a commercial electrodeless discharge lamp (EDL). The measurements were made using an echelle spectrometer and operating the lamps under a wide range of conditions. The line widths for the commercial HCL and for the EDL were found to be 0.91 pm (9.10 mÅ) and 0.895 pm (8.95 mÅ) respectively when operated under the recommended unpulsed operating conditions, and the EDL line was seven times as intense as that from the HCL. When the lamps were pulsed, the widths of the lines increased to 1.009 pm (10.09 mÅ) in the case of the HCL and to 0.904 pm (9.04 mÅ) for the EDL. The arsenic HCL, with neon as a carrier gas, suffers from severe spectral interference which arises from the presence of the 193.89 nm and 193.01 nm Ne II lines. This could account for most of the curvature of the absorbance-vs-concentration calibration curve.     

Probing thymine with laser ablation molecular beam Fourier transform microwave spectroscopy

Laser ablation in combination with molecular beam Fourier transform microwave spectroscopy has been used to establish unambiguously the presence of the diketo form of thymine in the gas phase and to obtain its structure.     

On the shape of atomic fluorescence analytical curves with a laser excitation source

The effect of high irradiance levels (approaching saturation) upon the shape of atomic fluorescence analytical curves is considered theoretically for both line and continuum sources. The linear range of the analytical curve may be greatly extended over that obtained with normal (low irradiance) sources, as is experimentally verified using a pulsed dye laser as an excitation source.     

The influence of hollow-cathode lamp line profiles upon analytical curves in atomic absorption spectroscopy

Analytical curves of Ca, Al, Mn, Ga and In in the acetylene-nitrous oxide flame are calculated using line profiles measured with a pressure-scanned interferometer. The effects of hyperflne structure, flame Une shift and finite hollow-cathode lamp line width are determined and found to decrease sensitivity by 10 to 20% and to bend the curves towards the concentration axis according to a quadratic function that causes deviations from a straight line between 2 and 7% at absorbance one. An increase of the lamp current from 5 to 25 mA d.c. enhances the effects mentioned above. It is shown that cooling the hollow cathode raises the sensitivity by only a few per cent and in some cases even reduces sensitivity. The use of a tunable laser as a primary source can improve sensitivity, especially when the atomic line profile consists of several widely spaced hyperfine components.     

Cooling and polarization of a sodium atomic beam by a two mode laser

Cooling and optical pumping by a circularly polarized two mode laser is applied to a Na atomic beam in transverse geometry. The low velocity components of the beam are transversly cooled to the Doppler limit temperature of 240 µK and are simultaneously spin polarized for more than 90%.     

Spectral profile of atomic emission lines and effects of pulse duration on laser ablation in liquid

The emission spectra of laser-ablated Cu atoms in water were examined, focusing on the irradiation-pulse duration effects. Spectral line profile was observed for the pulse duration of 19, 90, and 150 ns at various delay times. The line width as narrow as instrumental width was obtained by 150-ns pulse at the delay time of 800 ns. Also, long pulses result in high intensity of the emission. The spectral feature obtained by long pulses looks similar to that obtained in a gas phase. The absorption of the later part of the long pulse directly by the plume having been formed by the earlier part of the pulse may be the cause of this gas-phase-like emission. Whether the pulse heats directly the surface or the plume was investigated by the measurements of the removal volume of the ablation pit obtained by laser confocal scanning microscopy and the maximum bubble expansion size observed by shadowgraphy.