Chemical Mapping in the Mid- and Near-IR Spectral Regions by Hadamard Transform/FT-IR Spectrometry

Bellamy, Michael K.; Mortensen, A.; Hammaker, Robert M.; Fateley, William G.

doi:10.1366/0003702971940747

Cited by 30 publications

(5 citation statements)

References 33 publications

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“…Also, the HT is computationally simple to implement and is amenable to on-the-fly analysis when implemented by the simplified fast Hadamard transform. The use of the HT is perhaps best known for its successful application in optical spectrometry, where it is often implemented with a binary mask used to shield two-dimensional imaging detectors. − The Hadamard transform has also been successfully applied to separations by capillary electrophoresis (CE), where one example in the field produced an 8-fold S / N enhancement . The field of FT mass spectrometry has also seen the application of Hadamard techniques, − but the MS application most analogous to the IMS studies reported here combined the Hadamard transform with time-of-flight mass spectrometry (TOFMS) .…”

mentioning

confidence: 99%

Hadamard Transform Ion Mobility Spectrometry

2006

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A detection scheme that makes use of the Hadamard transform has been employed with an atmospheric-pressure ion mobility spectrometer fitted with an electrospray ionization source. The Hadamard transform was implemented through the use of a linear-feedback shift register to produce a pseudorandom sequence of 1023 points. This pseudorandom sequence was applied to the ion gate of the spectrometer, and deconvolution of the ion signal was accomplished by the Hadamard transform to reconstruct the mobility spectrum. Ion mobility spectra were collected in both a conventional and Hadamard mode, with comparisons made between the two approaches. Initial results exhibited low spectral definition, so an oversampling technique was applied to increase the number of data points across each analyte spectral peak. The use of the Hadamard transform increases the duty cycle of the instrument to 50% and results in a roughly 5-fold enhancement of the signal-to-noise ratio with a negligible loss of instrument resolution. It is also shown that any potential multiplex disadvantage, which limits the attractiveness of some high-throughput techniques, is not a limiting factor in this new implementation.

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confidence: 99%

Hadamard Transform Ion Mobility Spectrometry

2006

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“…What began as a one dimensional approach was extended to multi-dimensional problems [15][16][17], resulting in methods applicable to the RSM design optimization. Of particular interest is Bellamy et al's attempt to produce a two dimensional, moveable encoding mask [18]. Unfortunately, the mask positioning reproducibility difficulty and the mask's slow translation time hinder using moving mechanical masks in spectroscopy and imaging applications [17].…”

Section: Decoupling Andmentioning

confidence: 99%

Rotating scatter mask optimization for gamma source direction identification

Holland

Bevins

Burggraf

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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Rotating scattering masks have shown promise as an inexpensive, lightweight method with a large field-of-view for identifying the direction of a gamma emitting source or sources. However, further examination of the current rotating scattering mask design shows that changing the geometry may improve the identification by reducing or eliminating degenerate solutions and lower required count times. These changes should produce more linearly independent characteristics for the mask, resulting in a decrease in the mis-identification probability. Three approaches are introduced to generate alternative mask geometries. The eigenvector method uses a spring-mass system to create a geometry basis. The binary approach uses ones and zeros to represent the geometry with many possible combinations allowing for additional design flexibility. Finally, a Hadamard matrix is modified to examine a decoupled geometric solution. Four criteria are proposed for evaluating these methodologies. An analysis of the resulting detector response matrices demonstrates that these methodologies produced masks with superior identification characteristics than the original design. The eigenvector approach produces the least linearly dependent results, but exhibits a decrease in average efficiency. The binary results are more linearly dependent than the eigenvector approach, but this design achieves a higher average efficiency than original. The Hadamard-based method produced a lower maximum, but a higher average linear dependence than the original design. Further possible design enhancements are discussed.

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“…By using masks of known patterns or encoding, a large spatial area could be mapped to provide an effective multichannel advantage. Spatial multiplexing of the field of view can also be accomplished by the use of masks while retaining the advantages of the Fourier transform [126]. The process is schematically shown in Fig.…”

Section: Hadamard Transform Infrared Microscopymentioning

confidence: 99%

FTIR Microspectroscopy of Polymeric Systems

Bhargava

Wang

Koenig

2003

Liquid Chromatography / FTIR Microspectroscopy / Microwave Assisted Synthesis

134

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Fourier transform infrared (FTIR) spectroscopy is a mature analytical technique employed to examine polymeric materials. With the coupling of an infrared interferometer to a microscope equipped with specialized detectors, FTIR spectroscopy has been employed widely to examine microscopic areas in polymers for the last twenty years. Following the emergence of instrumentation techniques that employ focal plane array (FPA) detectors, FTIR microspectroscopy has experienced a recent renaissance in terms of the capability of instrumentation and visualization afforded for examining multicomponent polymer systems. We present an overview of the principles of instrumental configurations used to achieve spatially resolved spectral information, their relative advantages and limitations. Illustrative examples are presented that demonstrate the capabilities of FTIR microspectroscopy and the insight this technique provides into the composition, formation, and behavior of polymeric materials. Finally, some emerging techniques that may permit microspectroscopic analyses on a different spatial scale are reviewed.

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Chemical Mapping in the Mid- and Near-IR Spectral Regions by Hadamard Transform/FT-IR Spectrometry

Cited by 30 publications

References 33 publications

Hadamard Transform Ion Mobility Spectrometry

Hadamard Transform Ion Mobility Spectrometry

Rotating scatter mask optimization for gamma source direction identification

FTIR Microspectroscopy of Polymeric Systems

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