Studien zum Ramaneffekt

Reitz, A. W.; Skrabal, R.

doi:10.1007/bf01755681

Cited by 24 publications

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“…From these results, it is evident that Raman scattering from the C 18 chains bound to the surface of the silica particle is readily detected, with both methylene and methyl C-H stretching modes and CH 2 bending and twisting modes, as noted in the figure. Raman scattering from acetonitrile and water within the particle is also quite evident, where scattering from the CH (ν CH ) and CN (ν CN ) stretching vibrations of acetonitrile are observed at 2940 and 2253 cm -1 , respectively, 45,46 concentration, as expected, and illustrate the consistent quantitative response between sampled particles. The intensity of scattering from both the ν CN and ν CH modes of acetonitrile increases with the solution concentration of acetonitrile, but the increase in intensity is greater in the particle than in the solution surrounding the particle, suggesting that acetonitrile in the confocal volume is accumulating in the stationary phase.…”

Section: Resultssupporting

confidence: 69%

“…From these results, it is evident that Raman scattering from the C 18 chains bound to the surface of the silica particle is readily detected, with both methylene and methyl C−H stretching modes and CH 2 bending and twisting modes, as noted in the figure. Raman scattering from acetonitrile and water within the particle is also quite evident, where scattering from the CH (ν CH ) and CN (ν CN ) stretching vibrations of acetonitrile are observed at 2940 and 2253 cm −1 , respectively, , and the OH stretching from water (ν OH ) is found in a broad band, between 3100 and 3500 cm −1 , where the band centered around 3200 cm −1 corresponds to the symmetric stretch, ν s (OH), and the band at around 3450 cm −1 corresponds to the antisymmetric stretch, ν a (OH) …”

Section: Resultsmentioning

confidence: 99%

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Confocal Raman Microscopy of the Interfacial Regions of Liquid Chromatographic Stationary-Phase Materials

Gasser-Ramirez

Harris

2009

Anal. Chem.

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The influence of organic modifiers on the structure of reversed-phase liquid chromatographic (RPLC) stationary phases has been a topic of considerable investigation. Retention of organic modifiers in the stationary phase has previously been determined by chromatographic measurements, and the polarity and heterogeneity of the resulting solvation environment has been studied using solvatochromic, fluorescent, and spin probes. In the present work, the composition and solvation environment of a stationary phase is investigated using confocal Raman microscopy, which allows the in situ examination of the solvation environment within individual chromatographic stationary phase particles without the use of probe molecules. The accumulation of organic modifiers in the stationary phase can be quantified, and the environment of the modifier in the stationary phase can be determined. Specifically, we have investigated the interactions of acetonitrile with C(18)-functionalized silica particles using confocal Raman microscopy, which enables the sampling of small (approximately 1 fL) volumes within individual 10 microm particles. Bare chromatographic silica was also studied in order to investigate the interactions of acetonitrile with surface silanols. The nitrile-stretching (nu(CN)) frequency of acetonitrile responds sensitively to the dipolarity of its local microenvironment. The populations of solution-phase and interfacial acetonitrile are thus spectroscopically distinguishable. Scattering from nu(CN) shows contributions from three different environments within a single RPLC chromatographic particle: acetonitrile in the interparticle mobile phase, C(18)-chain associated acetonitrile, and acetonitrile that is interacting with residual surface silanols. Data are presented quantifying these populations and characterizing their environments within single stationary phase particles.

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Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Confocal Raman Microscopy of the Interfacial Regions of Liquid Chromatographic Stationary-Phase Materials

Gasser-Ramirez

Harris

2009

Anal. Chem.

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Infrared spectra of high polymers. VII. Polyacrylonitrile

1958

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The infrared spectrum of polyacrylonitrile has been obtained in the extended region of 70 to 3200 cm.−1 Polarized measurements were made on stretched and rolled specimens in the range of 350 to 3200 cm.−1. An analysis of the spectrum has been made on the basis of an atactic chain configuration, and has been shown to be in agreement with the observed data. Detailed assignments are proposed for all of the absorption bands in the spectrum, being aided by previous studies of high polymer spectra and by approximate normal frequency calculations for the nitrile group.

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Pure Liquids: Extended References

Wohlfarth¹,

Wohlfarth²

Refractive Indices of Inorganic, Organometallic, and Organononmetallic Liquids, and Binary Liquid Mixtures

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Studien zum Ramaneffekt

Cited by 24 publications

References 0 publications

Confocal Raman Microscopy of the Interfacial Regions of Liquid Chromatographic Stationary-Phase Materials

Confocal Raman Microscopy of the Interfacial Regions of Liquid Chromatographic Stationary-Phase Materials

Infrared spectra of high polymers. VII. Polyacrylonitrile

Pure Liquids: Extended References

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