Push-broom hyperspectral imaging for elemental mapping with glow discharge optical emission spectrometry

Gamez, Gerardo; Frey, Damian; Michler, Johann

doi:10.1039/c1ja10241a

Cited by 24 publications

(34 citation statements)

References 11 publications

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“…An additional point of comparison is the filter bandpass (∼3 nm), considerably larger than typical for the monochromatic imaging spectrometer 6 (∼1 nm), the acousto-optical spectrometer (<0.3 nm), 9 and the push-broom spectrometer (∼0.5 nm). 10…”

Section: Resultsmentioning

confidence: 99%

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Wavelength Scanning with a Tilting Interference Filter for Glow-Discharge Elemental Imaging

et al. 2016

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Glow discharges have long been used for depth profiling and bulk analysis of solid samples. In addition, over the past decade, several methods of obtaining lateral surface elemental distributions have been introduced, each with its own strengths and weaknesses. Challenges for each of these techniques are acceptable optical throughput and added instrumental complexity. Here, these problems are addressed with a tilting-filter instrument. A pulsed glow discharge is coupled to an optical system comprising an adjustable-angle tilting filter, collimating and imaging lenses, and a gated, intensified charge-coupled device (CCD) camera, which together provide surface elemental mapping of solid samples. The tilting-filter spectrometer is instrumentally simpler, produces less image distortion, and achieves higher optical throughput than a monochromator-based instrument, but has a much more limited tunable spectral range and poorer spectral resolution. As a result, the tilting-filter spectrometer is limited to single-element or two-element determinations, and only when the target spectral lines fall within an appropriate spectral range and can be spectrally discerned. Spectral interferences that result from heterogeneous impurities can be flagged and overcome by observing the spatially resolved signal response across the available tunable spectral range. The instrument has been characterized and evaluated for the spatially resolved analysis of glow-discharge emission from selected but representative samples.

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Section: Resultsmentioning

confidence: 99%

“…Accordingly, the latter two techniques are superior for imaging glow-discharge surfaces, in part because they boast high optical throughput. 9,10 The tilting-filter instrument described here further addresses this problem and with less instrumental complexity.…”

Section: Introductionmentioning

confidence: 99%

Wavelength Scanning with a Tilting Interference Filter for Glow-Discharge Elemental Imaging

et al. 2016

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“…EMCCD, CCD, etc.) or instruments capable of scanning an image across the entrance slit of a spectrometer [27]. Of course, if a single compromise spatial window were utilized, the method could be more readily expanded to instruments with single-channel detectors (such as a photomultiplier tube) or linear detector arrays.…”

Section: Compromise Window Spatial Selectionmentioning

confidence: 99%

Spatially resolved measurements to improve analytical performance of solution-cathode glow discharge optical-emission spectrometry

Schwartz

Ray

Chan

et al. 2016

Spectrochimica Acta Part B: Atomic Spectroscopy

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Past studies of the solution-cathode glow discharge (SCGD) revealed that elemental and molecular emission are not spatially homogenous throughout the source, but rather conform to specific zones within the discharge. Exploiting this inhomogeneity can lead to improved analytical performance if emission is collected only from regions of the discharge where analyte species emit strongly and background emission (from continuum, elemental and/or molecular sources) is lower. Effects of this form of spatial discrimination on the analytical performance of SCGD optical emission spectrometry (OES) have been investigated with an imaging spectrograph for fourteen atomic lines, with emphasis on detection limits and precision. Vertical profiles of the emission intensity, signal-to-background ratio, and signal-to-noise ratio were collected and used to determine the optimal region to view the SCGD on a per-element basis. With optimized spatial filtering, detection limits ranged from 0.09-360 ppb, a 1.4-13.6 fold improvement over those obtained when emission is collected from the full vertical profile (1.1-840 ppb), with a 4.2-fold average improvement. Precision was found to be unaffected by spatial filtering, ranging from 0.5-2.6% relative standard deviation (RSD) for all elements investigated, closely comparable to the 0.4-2.4% RSD observed when no spatial filtering is used. Spatial profiles also appear useful for identifying optimal line pairs for internal standardization and for flagging the presence of matrix interferences in SCGD-OES.

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“…At these large dimensions, evolved topography would be smoothed at the transition between adjacent materials; experimental evidence is given later. Relatively large surface heterogeneities are most relevant to glow discharge surfaceimaging techniques [17][18][19][20] , which typically offer spatial resolution on the scale of hundreds of micrometers. Finally, there is no guarantee that plasma conditions will be consistent during elemental analysis of a sample by imaging GD spectrometry.…”

Section: Program To Model Gd Sputtering Of Heterogeneous Materialsmentioning

confidence: 99%

“…Over the past decade, several optical techniques have been developed to view spatially resolved emission across the surface of glow discharge samples. [17][18][19][20] These techniques utilize pulsed glow discharges in 0.1 to 4.0 kPa of argon to temporally and spatially isolate emitting species near where they were sputtered from the surface. Higher pressures shrink the mean free path, which limits the lateral diffusion of atoms in the time between their removal from a sample surface and emission they yield in the negative glow region of the discharge.…”

Section: Introductionmentioning

confidence: 99%

Emergence and consequences of lateral sample heterogeneity in glow discharge spectrometry

Storey

Ray

Hoffmann

et al. 2016

Spectrochimica Acta Part B: Atomic Spectroscopy

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Conventional glow discharge emission or mass spectrometry requires the assumption that the surface of the sample is homogeneous. However, recent developments in glow discharge imaging appear to offer an opportunity to obtain three-dimensional concentration maps, in which this assumption is no longer necessary. Here, experiments, models, and a summary of earlier work are combined to examine the sputtering behavior of elemental and morphological heterogeneities in a sample. The theoretical model reveals gaps in current knowledge of glow discharge sputtering of heterogeneous samples, particularly indicating that heterogeneity in the sample leads to roughened crater bottoms and how additional morphology can evolve. Additionally, a three-dimensional profiling microscope is used to characterize the effects of surface inclusions on the sputtering process in a DC glow discharge in a reduced-pressure argon environment. Findings have important implications for bulk analysis, depthprofiling, and elemental surface mapping with glow discharge spectrometry.

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Push-broom hyperspectral imaging for elemental mapping with glow discharge optical emission spectrometry

Cited by 24 publications

References 11 publications

Wavelength Scanning with a Tilting Interference Filter for Glow-Discharge Elemental Imaging

Wavelength Scanning with a Tilting Interference Filter for Glow-Discharge Elemental Imaging

Spatially resolved measurements to improve analytical performance of solution-cathode glow discharge optical-emission spectrometry

Emergence and consequences of lateral sample heterogeneity in glow discharge spectrometry

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