Depth Profiling of the Degree of Cure during the Photopolymerization of Acrylates Studied by Real-Time FT-IR Attenuated Total Reflection Spectroscopy

2002 ◽  
Vol 56 (11) ◽  
pp. 1403-1412 ◽  
Author(s):  
Tom Scherzer
Keyword(s):  
Real Time ◽  
Depth Profiling ◽  
Finite Depth ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Depth Of Penetration ◽  
Degree Of Cure ◽  
Uv Absorbers ◽  
Ft Ir ◽  
Atr Spectroscopy

Real-time Fourier transform infrared attenuated total reflection (FT-IR/ATR) spectroscopy was used to study the depth profile of the conversion during photopolymerization reactions. The method is based on the UV irradiation of coatings of different thicknesses on the ATR crystal. Due to the finite depth of penetration of the infrared probe signal into the sample, conversion is analyzed only in a narrow layer at the bottom of the coating. The method was used to characterize the effect of photo-initiators on the depth of cure in acrylate coatings. The self-screening of a strongly absorbing morpholino ketone photo-initiator and the photobleaching of a bisacylphosphine oxide initiator are demonstrated. Moreover, depth profiling studies on the filter effect of UV absorbers and on the influence of pigmentation in white-pigmented systems will be reported.

Discrimination of Soil-Borne Fungi Using Fourier Transform Infrared Attenuated Total Reflection Spectroscopy

2008 ◽  
Vol 62 (3) ◽  
pp. 302-305 ◽  
Author(s):  
Raphael Linker ◽  
Leah Tsror(LAHKIM)
Keyword(s):  
Fourier Transform ◽  
Success Rate ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Economic Damage ◽  
Genus Level ◽  
Ft Ir ◽  
Atr Spectroscopy ◽  
Soil Borne Fungi

Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy was used to discriminate five commonly encountered soil-borne fungi that cause severe economic damage to agriculture: Colletotrichum, Fusarium, Pythium, Rhizoctonia, and Verticillium. Contrary to previous studies related to microorganism discrimination using FT-IR-ATR spectroscopy, the pathogen samples were not dried on the ATR crystal, which is a time-consuming operation. Rather, after removing some pathogen filaments from the solution using tweezers, these were placed directly on a flat ATR crystal and pressure was applied using a pressure clamp. Following water subtraction, baseline correction, and normalization of the spectra, principal component analysis was used as a data-reduction step and canonical variate analysis was used for discrimination. Discrimination was performed at the genus level and at the strain level for Colletotrichum. For discrimination between the five fungi at the genus level, the success rate for the validation samples ranged from 75% to 89%. For discrimination between the two Colletotrichum strains, the success rate was 78%. Comparison with spectra of similar fungi dried on the ATR crystal showed that both types of spectra were very similar, indicating that drying the samples on the ATR crystal is not required and can be replaced by mathematical post-processing of the spectra. For routine analyses that involve rapid screening of very large amounts of samples, this approach allows for increasing significantly the number of samples that can be analyzed daily.

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.

Attenuated Total Reflection—Fourier Transform Infrared Imaging of Large Areas Using Inverted Prism Crystals and Combining Imaging and Mapping

2008 ◽  
Vol 62 (10) ◽  
pp. 1095-1101 ◽  
Author(s):  
K. L. Andrew Chan ◽  
Sergei G. Kazarian
Keyword(s):  
Fourier Transform ◽  
Spatial Resolution ◽  
Infrared Imaging ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Array Detector ◽  
Aqueous Environment ◽  
Depth Of Penetration ◽  
Ft Ir

Attenuated total reflection–Fourier transform infrared (ATR-FT-IR) imaging is a very useful tool for capturing chemical images of various materials due to the simple sample preparation and the ability to measure wet samples or samples in an aqueous environment. However, the size of the array detector used for image acquisition is often limited and there is usually a trade off between spatial resolution and the field of view (FOV). The combination of mapping and imaging can be used to acquire images with a larger FOV without sacrificing spatial resolution. Previous attempts have demonstrated this using an infrared microscope and a Germanium hemispherical ATR crystal to achieve images of up to 2.5 mm × 2.5 mm but with varying spatial resolution and depth of penetration across the imaged area. In this paper, we demonstrate a combination of mapping and imaging with a different approach using an external optics housing for large ATR accessories and inverted ATR prisms to achieve ATR-FT-IR images with a large FOV and reasonable spatial resolution. The results have shown that a FOV of 10 mm × 14 mm can be obtained with a spatial resolution of approximately 40–60 μm when using an accessory that gives no magnification. A FOV of 1.3 mm × 1.3 mm can be obtained with spatial resolution of approximately 15–20 μm when using a diamond ATR imaging accessory with 4× magnification. No significant change in image quality such as spatial resolution or depth of penetration has been observed across the whole FOV with this method and the measurement time was approximately 15 minutes for an image consisting of 16 image tiles.

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.

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