Chemical Microscopy

Cooke, Peter M.

doi:10.1021/a1980009x

Cited by 10 publications

(6 citation statements)

References 286 publications

(182 reference statements)

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“…Energy dispersive spectroscopy (EDS) was also used for qualitative analysis of the surface changes to the NCS after exposure to orthophosphate [32].…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Calcium–phosphorus interactions at a nano-structured silicate surface

Southam

Lewis

McFarlane

et al. 2008

Journal of Colloid and Interface Science

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Nano-structured calcium silicate (NCS), a highly porous material synthesized by controlled precipitation from geothermal fluids or sodium silicate solution, was developed as filler for use in paper manufacture. NCS has been shown to chemisorb orthophosphate from an aqueous solution probably obeying a Freundlich isotherm with high selectivity compared to other common environmental anions. Microanalysis of the products of chemisorption indicated there was significant change from the porous and nano-structured morphology of pristine NCS to fibrous and crystalline morphologies and non-porous detritus. X-ray diffraction analysis of the crystalline products showed it to be brushite, CaHPO42H2O, while the largely X-ray amorphous component was a mixture of calcium phosphates. A two-step mechanism was proposed for the chemisorption of phosphate from an aqueous solution by NCS. The first step, which was highly dependent on pH, was thought to be desorption of hydroxide ions from the NCS surface. This was kinetically favoured at lower initial pH, where the predominant form of phosphate present was H2PO(-)4, and led to decreased phosphorus uptake with increasing pH. The second step was thought to be a continuing chemisorption process after stabilization of the pH-value. The formation of brushite as the primary chemisorption product was found to be consistent with the proposed mechanism.

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“…Energy dispersive spectroscopy (EDS) was also used for qualitative analysis of the surface changes to the NCS after exposure to orthophosphate [32].…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Calcium–phosphorus interactions at a nano-structured silicate surface

Southam

Lewis

McFarlane

et al. 2008

Journal of Colloid and Interface Science

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“…A wide range of analytical methods and instrumental techniques for screening and identifying the suspected counterfeits have been developed. − Raman microscopy is one of the favored techniques, since it is typically nondestructive and it provides a wealth of molecular-level information on the materials or objects being analyzed. − As such, identification of specific analytes leading to authentication is made possible. Raman array microscopy in particular, which integrates spectroscopy with mapping and imaging technology, has the capability to generate hundreds or even thousands of Raman spectra from one specific area of sample. However, visual examination of all the collected spectra in one area is neither practical nor sufficient for many purposes, and thus, more sophisticated techniques for rapid but detailed objective analysis of the data is needed.…”

mentioning

confidence: 99%

Use of Raman Microscopy and Band-Target Entropy Minimization Analysis To Identify Dyes in a Commercial Stamp. Implications for Authentication and Counterfeit Detection

Widjaja

Garland

2008

Anal. Chem.

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Raman microscopy was used in mapping mode to collect more than 1000 spectra in a 100 microm x 100 microm area from a commercial stamp. Band-target entropy minimization (BTEM) was then employed to unmix the mixture spectra in order to extract the pure component spectra of the samples. Three pure component spectral patterns with good signal-to-noise ratios were recovered, and their spatial distributions were determined. The three pure component spectral patterns were then identified as copper phthalocyanine blue, calcite-like material, and yellow organic dye material by comparison to known spectral libraries. The present investigation, consisting of (1) advanced curve resolution (blind-source separation) followed by (2) spectral data base matching, readily suggests extensions to authenticity and counterfeit studies of other types of commercial objects. The presence or absence of specific observable components form the basis for assessment. The present spectral analysis (BTEM) is applicable to highly overlapping spectral information. Since a priori information such as the number of components present and spectral libraries are not needed in BTEM, and since minor signals arising from trace components can be reconstructed, this analysis offers a robust approach to a wide variety of material problems involving authenticity and counterfeit issues.

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“…Due to its noninvasiveness, Fourier transform IR microspectroscopy ͑micro FTIR͒ is probably the most popular method for chemical microscopy. 1,2 The region of the infrared spectrum which is of greatest interest is the wavelength range 2.5-20 m (4000-500 cm Ϫ1 ), although the near infrared also has recent applications. 3 The region beyond 5 m (2000 cm Ϫ1 ) can become quite complex and is often referred to as the ''fingerprint region.''…”

Section: A Classical Infrared Microspectroscopymentioning

confidence: 99%

Pattern characterization of deep-ultraviolet photoresists by near-field infrared microscopy

Dragnea

Preusser

Szarko

et al. 2001

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Partially hydrogenated poly(vinyl phenol) based photoresist for near UV, high aspect ratio micromachining Chemical contrast at subwavelength spatial resolution ͑/10͒ is achieved using a fiber-based, infrared near-field microscope, at 3 m wavelength. Chemically amplified polymer photoresists ͑poly͑t-butylmethacrylate͒͒, patterned by ultraviolet radiation and 250 nm thick, are imaged using infrared ͑IR͒ wavelengths situated around the OH stretch band of the polymer, a region sensitive to photochemical changes associated with latent image formation. The key technical points that enable near-field infrared absorption measurements down to 0.05% absorption sensitivity are discussed together with the major contrast mechanisms involved in image formation. The measurements are complemented by confirming studies using confocal infrared microscopy and depth profiling. The exposure dose dependence of the acid catalyzed chemistry, after the postexposure bake step, was studied on line/space patterned samples. The OH subgroup absorption maps of the patterned polymer film exhibit features that are not present in the topographical changes ͑shrinkage͒ induced by the postexposure polymer chemistry and illustrate significant potential of the IR near-field microscopy as an analytical tool for polymer chemical physics.

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Chemical Microscopy

Cited by 10 publications

References 286 publications

Calcium–phosphorus interactions at a nano-structured silicate surface

Calcium–phosphorus interactions at a nano-structured silicate surface

Use of Raman Microscopy and Band-Target Entropy Minimization Analysis To Identify Dyes in a Commercial Stamp. Implications for Authentication and Counterfeit Detection

Pattern characterization of deep-ultraviolet photoresists by near-field infrared microscopy

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