scholarly journals Evaluation of Silicon Wafer-Based Internal Reflection Elements for Use with in Situ Fourier Transform Infrared (FT-IR) Spectroscopy

2018 ◽  
Vol 72 (9) ◽  
pp. 1396-1403 ◽  
Author(s):  
Brent A. Sperling ◽  
Berc Kalanyan
Keyword(s):  
Silicon Wafer ◽  
Polarization State ◽  
Cell Polarization ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Ft Ir ◽  
Atr Spectroscopy ◽  
Lower Noise ◽  
Ft Ir Spectroscopy

Silicon wafer-based internal reflection elements (IREs) present many practical advantages over the prisms conventionally used for attenuated total reflection (ATR) spectroscopy in the infrared. We examine two methods of using minimally prepared IREs that have appeared in the literature, edge-coupled (EC) and prism-coupled (PC), in conjunction with a liquid flow cell. Polarization measurements show that radiation entering the PC-IRE becomes depolarized due to stress-induced birefringence, and transmission through the edge of the EC-IRE also affects the polarization state. Quantification of the noise and a calibration using a series of sodium acetate solutions show the sensitivity of the PC-IRE outweighs the lower noise obtainable with the EC-IRE.

Attenuated (but Not Total) Internal Reflection FT-IR Spectroscopy of Thin Films

2002 ◽  
Vol 56 (5) ◽  
pp. 665-669 ◽  
Author(s):  
Will Cantrell ◽  
George E. Ewing
Keyword(s):  
Theoretical Basis ◽  
Total Internal Reflection ◽  
Spectroscopic Technique ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Geometric Constraints ◽  
Ft Ir ◽  
Atr Spectroscopy ◽  
Ft Ir Spectroscopy

We present a spectroscopic technique that is a hybrid between reflection-absorption and attenuated total reflection (ATR) spectroscopy. The method, which we call attenuated internal reflection (AIR), is suitable for the investigation of thin film liquids on non-or weakly absorbing substrates. In AIR the interrogating infrared beam is not exposed to vapor that may be associated with the film, but unlike ATR there are few geometric constraints on the substrate. We show the theoretical basis for the method and results from experiments demonstrating its use.

In Situ Studies of Coatings on Metal Wires by FT-IR External Reflectance Spectroscopy

1987 ◽  
Vol 41 (7) ◽  
pp. 1172-1175 ◽  
Author(s):  
Gi Xue ◽  
Shi-Ying Liu ◽  
Yi Jin ◽  
Shan-Geng Jiang
Keyword(s):  
Diffuse Reflectance ◽  
Collection Efficiency ◽  
Scattered Light ◽  
Attenuated Total Reflection ◽  
Light Collection ◽  
Wire Sample ◽  
Ft Ir ◽  
Metal Wires ◽  
Ft Ir Spectroscopy

Diffuse reflectance FT-IR spectroscopy was originally developed for particulate samples dispersed in KBr powders. Now, by using ellipsoid mirrors for scattered light collection, we have taken advantage of the collection efficiency of diffuse reflectance optics and have extended their use to an in situ study of coatings on metal wires and of the broken surface of a reinforcement wire as well. The result is that spectra of coatings on wire show good overall agreement with external reflection spectra of thin films. The technique we have developed has an advantage over infrared attenuated total reflection (ATR), in that there is no optical contact problem between the wire sample and ATR crystal.

scholarly journals Mesoporous Zirconia Coating for Sensing Applications Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy

2021 ◽  
pp. 000370282110571
Author(s):  
Dominik Wacht ◽  
Mauro David ◽  
Borislav Hinkov ◽  
Hermann Detz ◽  
Andreas Schwaighofer ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Ir Spectroscopy ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
In Situ Monitoring ◽  
Zirconia Coating ◽  
Mesoporous Zirconia ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Mid-infrared attenuated total reflection (ATR) spectroscopy is a powerful tool for in situ monitoring of various processes. Mesoporous silica, an extensively studied material, has already been applied in sensing schemes due to its high surface area and tunable surface chemistry. However, its poor chemical stability in aqueous solutions at pH values higher than 8 and strong absorption below 1250 cm−1 limits its range of applications. To circumvent these problems, a mesoporous zirconia coating on ATR crystals was developed. Herein, the synthesis, surface modification, and characterization of ordered mesoporous zirconia films on Si wafers and Si-ATR crystals are presented. The modified coating was applied in sensing schemes using aromatic and aliphatic nitriles in aqueous solution as organic pollutants. The mesoporous zirconia coating shows strong chemical resistance when kept in alkaline solution for 72 h. The success of surface modification is confirmed using Fourier transform infrared (FT-IR) spectroscopy and contact angle measurements. Benzonitrile and valeronitrile in water are used as model analytes to evaluate the enrichment performance of the film. The experimental results are fitted using Freundlich isotherms, and enrichment factors of 162 and 26 are calculated for 10 mg L−1 benzonitrile and 25 mg L−1 valeronitrile in water, respectively. Limits of detection of 1 mg L−1 for benzonitrile and 11 mg L−1 for valeronitrile are obtained. The high chemical stability of this coating allows application in diverse fields such as catalysis with the possibility of in situ monitoring using FT-IR spectroscopy.

Optical Contact in ATR/FT-IR Spectroscopy

2001 ◽  
Vol 55 (10) ◽  
pp. 1352-1359 ◽  
Author(s):  
Sanong Ekgasit ◽  
Adchara Padermshoke
Keyword(s):  
Ir Spectroscopy ◽  
Air Gap ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Experimental Investigations ◽  
Transmission Spectra ◽  
Optical Contact ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Optical contact between an internal reflection element (IRE) and a sample is crucial for obtaining a good spectrum in an attenuated total reflection (ATR) experiment. When an air gap is present between the IRE and the sample, the spectrum severely deteriorates. Two techniques for determining the goodness of contact are proposed—first, by making a comparison between polarized ATR spectra and, second, by making a comparison between ATR and transmission spectra. When the optical contact is achieved, the normalized p-polarized ATR spectrum is exactly the same as the normalized s-polarized ATR spectrum. Moreover, the ratio between the normalized absorbance measured in the ATR mode and the normalized absorbance measured in the transmission mode equals the ratio between the frequency being considered and the normalization frequency. Theoretical and experimental investigations have been performed in order to verify the proposed techniques.

scholarly journals Fatty Acid Prediction in Bovine Milk by Attenuated Total Reflection Infrared Spectroscopy after Solvent-Free Lipid Separation

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1054
Author(s):  
Christopher Akhgar ◽  
Vanessa Nürnberger ◽  
Marlene Nadvornik ◽  
Margit Velik ◽  
Andreas Schwaighofer ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Milk Fat ◽  
Regression Models ◽  
Bovine Milk ◽  
Attenuated Total Reflection ◽  
Solvent Free ◽  
Novel Approach ◽  
Whole Milk ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

In the present study, a novel approach for mid-infrared (IR)-based prediction of bovine milk fatty acid composition is introduced. A rapid, solvent-free, two-step centrifugation method was applied in order to obtain representative milk fat fractions. IR spectra of pure milk lipids were recorded with attenuated total reflection Fourier-transform infrared (ATR-FT-IR) spectroscopy. Comparison to the IR transmission spectra of whole milk revealed a higher amount of significant spectral information for fatty acid analysis. Partial least squares (PLS) regression models were calculated to relate the IR spectra to gas chromatography/mass spectrometry (GC/MS) reference values, providing particularly good predictions for fatty acid sum parameters as well as for the following individual fatty acids: C10:0 (R2P = 0.99), C12:0 (R2P = 0.97), C14:0 (R2P = 0.88), C16:0 (R2P = 0.81), C18:0 (R2P = 0.93), and C18:1cis (R2P = 0.95). The IR wavenumber ranges for the individual regression models were optimized and validated by calculation of the PLS selectivity ratio. Based on a set of 45 milk samples, the obtained PLS figures of merit are significantly better than those reported in literature using whole milk transmission spectra and larger datasets. In this context, direct IR measurement of the milk fat fraction inherently eliminates covariation structures between fatty acids and total fat content, which poses a common problem in IR-based milk fat profiling. The combination of solvent-free lipid separation and ATR-FT-IR spectroscopy represents a novel approach for fast fatty acid prediction, with the potential for high-throughput application in routine lab operation.

Diffusion Measurements Using FT-IR ATR Spectroscopy: Lubricant Diffusion in Polypropylene

2002 ◽  
Vol 56 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Xiaohua Yi ◽  
Karen Nerbonne ◽  
John Pellegrino
Keyword(s):  
Current Model ◽  
Mineral Oil ◽  
Attenuated Total Reflection ◽  
Lubricant Layer ◽  
Polymer Interfaces ◽  
Time Resolved ◽  
Polymer Sample ◽  
Ft Ir ◽  
Atr Spectroscopy ◽  
Poly Propylene

We present an experimental method for measuring diffusion of lubricants (or any highly viscous fluid) in polymers using Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy. Unlike the conventional FT-IR ATR diffusion measurement, in which a polymer sample is sandwiched between the penetrant and an internal reflection element (IRE), in this method, a thin layer of penetrant (for example, a lubricant) is sandwiched between the IRE and the polymer sample. This allows accurate control and measurement of the thickness of the lubricant layer, which, in turn, facilitates subsequent data analysis. The diffusion is studied by monitoring the time-resolved change in absorbance of either a unique polymer or penetrant band. A feature of this new method is that it can provide an estimate of solubility, as well as an estimate of the diffusivity of the penetrant in the polymer. Using this method, we studied the diffusion of mineral oil and a commercial fluorocarbon ether lubricant (Krytox® 143AC‡) in poly(propylene) (PP) film at room temperature. The experimental data was modeled using a Fickian model with impermeable and saturated boundary conditions applied at the IRE/lubricant and lubricant/polymer interfaces, respectively. The diffusivity and solubility of mineral oil in PP were found to be 1.34 ± 0.35 (×10−10) cm2/s and 0.77 ± 0.13 (×10−2) g/g of PP, respectively. The current model was unable to quantitatively describe the diffusion of the Krytox® 143AC in the PP, possibly due to excessive swelling.

scholarly journals Simultaneous Infrared Spectroscopy, Raman Spectroscopy and Luminescence Sensing: A Multi-Spectroscopic Analyti-cal Platform

2021 ◽  
Author(s):  
Sarah Klingler ◽  
Julian Hniopek ◽  
Robert Stach ◽  
Michael Schmitt ◽  
Jürgen Popp ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Environmental Chemistry ◽  
Attenuated Total Reflection ◽  
Liquid Volume ◽  
On Line ◽  
Atr Spectroscopy ◽  
Gas Tight ◽  
Scientific Questions ◽  
Minute Sample

Scientific questions in fields such as catalysis, monitoring of biological processes or environmental chemistry demand for analytical technologies combining orthogonal spectroscopies. Combined spectroscopic concepts facilitate in-situ on-line monitoring of dynamic processes providing for a better understanding of the involved reaction pathways. In the present study, a low-liquid-volume multi-spectroscopic platform was developed based on infrared attenuated total reflection (IR-ATR) spectroscopy combined with Raman spectroscopy and lumines-cence sensing. For demonstrating the measurement capabilities, exemplary analyte systems including water / heavy water and aqueous solutions of ammonium sulfate were analyzed as proof-of-principle studies. It was successfully demonstrated that three optical techniques may be integrated into a single analytical platform with-out interference providing synchronized and complementary datasets by probing the same minute sample vol-ume. In addition, the developed assembly provides a gas-tight lid sealing the headspace above the probed liq-uid for monitoring the concentration of molecular oxygen also in the gas phase via luminescence quenching. Hence, the entire assembly may be operated at inert conditions, as required for example during the analysis of photocatalytic processes.

scholarly journals Monitoring the Interfacial Polymerization of Piperazine and Trimesoyl Chloride with Hydrophilic Interlayer or Macromolecular Additive by in-situ FT-IR Spectroscopy

2019 ◽  
Author(s):  
Xi Yang
Keyword(s):  
Ir Spectroscopy ◽  
Reaction Rate ◽  
Interfacial Polymerization ◽  
Reaction System ◽  
Reaction Rates ◽  
Water Permeation ◽  
Ft Ir ◽  
Trimesoyl Chloride ◽  
Ft Ir Spectroscopy

The interfacial polymerization (IP) of piperazine (PIP) and trimesoyl chloride (TMC) has been extensively utilized to synthesize the nanofiltration (NF) membrane. However, it is still a huge challenge to monitor the IP reaction, because of the fast reaction rate and the formed ultra-thin film. Herein, two effective strategies are applied to reduce the IP reaction rate: (1) the introduction of hydrophilic interlayers between the porous substrate and the formed polyamide layer; (2) the addition of macromolecular additives in the aqueous solution of PIP. As a result, in-situ FT-IR spectroscopy was firstly used to monitor the IP reaction of PIP/TMC reaction system, with hydrophilic interlayers or macromolecular additives. Moreover, we study the formed polyamide layer growth on the substrate, in a real-time manner. The in-situ FT-IR experimental results confirm that the IP reaction rates are effectively suppressed and the formed polyamide thickness reduces from 138±24 nm to 46±2 nm. Furthermore, the optimized NF membrane with excellent performance are consequently obtained, which include the boosted water permeation flux about 141~238 (L·m2·h/MPa) and superior salt rejection of Na2SO4 > 98.4%.

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