Precision measurement of L X-ray wavelenghts and line widths for 74 ≦ Z ≦ 95 and their interpretation in terms of nuclear perturbations

Merrill, John J.; DuMond, Jesse W. M.

doi:10.1016/0003-4916(61)90057-4

Cited by 37 publications

(2 citation statements)

References 31 publications

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“…There should be, in principle, small corrections for crystal asymmetry and other spectrometer window effects, which have been studied in detail by Merrill and DuMond, 18 Sauder,26 and Marzolf. 27 This could affect first-order calcite measurements of Cr Ka 2 by the order of 5 ppm.…”

Section: Discussionmentioning

confidence: 99%

Precision Redetermination of Standard Reference Wavelengths for X-Ray Spectroscopy

et al. 1964

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This investigation is designed to determine with high accuracy the wavelength ratios of 5 standard x-ray reference lines: Cr Ka2, Cu Kai, Mo Kai, Ag Kai, and W Kai. Most measurements were obtained with a double-crystal spectrometer in reflection. However, a few were taken with the instrument converted to a high-precision single-crystal spectrometer, and some tungsten determinations were made in transmission. Since estimated errors (± 1 ppm) are the lowest ever claimed for this type of work, the apparatus, including adjustment, calibration, and corrections, are described in considerable detail. Novel features include: use of a high-intensity, narrow-focus rotating-target tube for most measurements, calibration of the spectrometer circle to 0.1 sec with an angular interferometer, and a careful selection of 5 crystals (1 calcite, 2 quartz, and 2 silicon) from more than 100 samples tested. Bragg angles were determined for 20 different combinations of crystals and wavelengths. With an assumed wavelength value for one selected line, this gave an overdetermined set of 20 equations for 9 unknowns (4 wavelengths and 5 grating constants), which was solved by a least-squares adjustment. If the value for Mo Kai is provisionally taken as 707.831 xu, the resulting values for the other wavelengths are: Cr Ka 2 , 2288.854±0.003 xu; Cu Kai, 1537.370±0.002 xu; Ag Kai, 558.2486 ±0.0006 xu; W Kai, 208.5770±0.0003 xu. However, the primary quantities determined are the wavelength ratios, which are invariant with respect to a choice of the primary defining reference line. The question of adopting a definitive standard is left open for the present.

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Section: Discussionmentioning

confidence: 99%

Precision Redetermination of Standard Reference Wavelengths for X-Ray Spectroscopy

et al. 1964

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“…The Cauchois type spectrometer places the source on the convex side of the bent crystal, a large area detector is placed on the opposite side of the crystal and on the RC, and the fixed detector records a spectrum with a relatively wide energy coverage [5]. The Dumond type spectrometer places the source on or near the RC on the concave side of the bent crystal, a wide extent of the crystal diffracts rays of a selected energy, and a detector on the opposite side of the crystal and behind a narrow slit is scanned through the dispersed spectrum [6]. Spectrometers of the two types that are each optimally designed for a specific application, and that have the same energy resolution and other corresponding capabilities, require the same data accumulation time to record equivalent spectra over a specified energy range.…”

Section: Spectrometer and Diffraction Crystal Geometrymentioning

confidence: 99%

Measurement of the O2O3O4 and O3O4O5 super Coster–Kronig rates in tungsten via asymmetric diffraction spectrometry

Seely

Glover

Hudson

et al. 2014

J. Phys. B: At. Mol. Opt. Phys.

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The tungsten Lγ transitions between 11 and 12 keV and Kα transitions from 57 to 60 keV were produced by a laboratory electron-bombarded x-ray source and simultaneously recorded with high resolution by using multiple diffraction planes of the same quartz crystal operating in Cauchois transmission geometry. The W Kα transitions were dispersed by the (5 0 2) planes, which were perpendicular to the crystal entrance surface, and by the (6 0 2), (7 0 2), and (8 0 4) planes which were rotated with respect to the (5 0 2) planes by angles up to 4.80 • . The W Lγ transitions were dispersed by the (2 0 1) planes rotated from the (5 0 2) planes by 4.01 • . The spectra from the five planes were simultaneously recorded on image plate detectors, and spectra were also recorded by scanning solid-state electronic detectors with narrow slits across the spectral lines. The metrology of the L and K shell spectra diffracted from multiple quartz planes enabled the detailed analysis of the detector spatial resolution and accurate measurement of the instrumental broadening produced by the various quartz diffraction planes. The W Lγ spectra had the highest instrumental resolving power, 1800, permitting for the first time the resolution of the blended Lγ 4 (L1O2) and Lγ 4 (L1O3) transitions. After subtracting the instrumental and detector contributions to the line widths, the remainder was assigned to the natural line widths. The measured widths of the O2 and O3 levels were 2.9 eV and 1.9 eV, respectively, and based on atomic code calculations these widths are attributed to the O2O3O4 and O3O4O5 super Coster-Kronig processes. This work demonstrates the ability to simultaneously record high resolution (<1 eV) L and K spectra to determine the line shapes of the heavy elements (e.g. W through Am) by using multiple planes of a single quartz crystal and to accurately measure the non-radiative super Coster-Kronig rates which are closely related to the energy level structure of the outer shells of the heavy elements.

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Atomic level widths for x‐ray spectrometry

Campbell

Papp

1995

X-Ray Spectrometry

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A self-consistent set of level widths for the K-N7 subshells is assembled using literature experimental data from a variety of spectroscopic methods. In cases where Coster-Kronig processes contribute significantly, the widths differ from the predictions of the atomic single-particle model; in the restricted regions where atomic many-body predictions are available, the agreement is much better. The assembled widths will he useful to Si(Li) spectroscopists who wish to include natural width in the description of spectrometer lineshape; such inclusion will improve accuracy in both fundamental and analytical work. The present database is also of value in identifying where improvements to the currently incomplete knowledge of natural widths are most critical. LINESHAPES IN Si(Li) AND Ge SPECTROMETERSThe lineshape resulting from the interaction of x-rays of a given energy with an Si(Li) or Ge detector is, in principle, Gaussian, reflecting the Fano statistics of electron-hole formation together with the effects of noise. In practice, this simple Gaussian description of lineshape has to be augmented by exponential and shelf-like features' on the low-energy side of peaks. These are empirical descriptions for the sum of a variety of complex effects. Auger electrons and photoelectrons created by the interaction of an x-ray with a silicon atom can escape from the front surface of the detector, only a fraction of their energy then being converted to hole-electron pairs. If the x-ray interacts in the front metallic contact, the resulting Auger and photoelectrons may penetrate to the sensitive silicon region, depositing a fraction of their energy there. The cloud of ionization electrons (sometimes referred to as hot electrons) created in turn by the Auger and photoelectrons diffuses, and a portion of this cloud may be lost through the front surface of the detector. In addition to these inevitable physical processes, defects may exist in the silicon, especially in the proximity of the front contact, and charge carriers may be trapped there, resulting in degraded events.An accurate description of these tailing features provides improved fits of model spectra to measured spectra, and therefore improves the accuracy of x-ray emission analysis techniques such as XRF and PIXE.In addition to these various effects, which can be subsumed under the rubric of incomplete charge collection, there are two fundamental sources of low-energy events accompanying a peak in an Si(Li) spectrum. The first is the radiative Auger effect; here the atomic excitation energy is shared between an x-ray photon and an Auger electron, and so the diagram line is accompanied by a weak low-energy satellite structure. While attempts are sometimes made to describe this effect within the overall lineshape, it has been customary to neglect entirely a second fundamental source of tailing, viz. the natural Lorentzian shape of the energy distribution of any characteristic x-ray excited well above the threshold energy. This shape is rJ2nwhere the lifetime broadening r i...

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Precision measurement of L X-ray wavelenghts and line widths for 74 ≦ Z ≦ 95 and their interpretation in terms of nuclear perturbations

Cited by 37 publications

References 31 publications

Precision Redetermination of Standard Reference Wavelengths for X-Ray Spectroscopy

Precision Redetermination of Standard Reference Wavelengths for X-Ray Spectroscopy

Measurement of the O2O3O4 and O3O4O5 super Coster–Kronig rates in tungsten via asymmetric diffraction spectrometry

Atomic level widths for x‐ray spectrometry

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