Photoacoustic spectroscopy FT-IR-PAS

Microphonic Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has emerged as a useful tool for characterizing fractions of a monolayer of organic species adsorbed on opaque, high surface area samples. Such a study of calcined and sulfided hydrodesulfurization catalysts will be discussed. 

Fourier transform infrared/photoacoustic spectroscopy (FT-IR/PAS) can be used to evaluate the secondary structure of proteins, as demonstrated by experiments on concanavalin A, hemoglobin, lysozyme, and trypsin, four proteins having different distributions of secondary... 

A variety of cellulose textile materials, including sized cotton yarns and chemically treated cotton fabrics were studied with fourier transform Infrared photoacoustic spectroscopy (FT-IR/PAS) in our laboratory. The distribution of chemical additives into cotton yarns and fabrics was determined using FT-IR/PAS. It is concluded that FT-IR/PAS is a non-destructive and information-rich analytical technique which is uniquely suitable to the near-surface characterization of a variety of cellulose textile materials. The fundamentals of FT-IR/PAS are also reviewed. 

Fourier Transform Infrared Photoacoustic Spectroscopy (FT-IR-PAS) has been developed recently. In this technique the standard... 

FT-IR photoacoustic spectroscopy (PAS) is rapidly gaining acceptance as a useful technique for the study of gases, liquids and solids. Most of the earlier references to the work on the PAS technique have been reviewed by Krishnan (11). Some of the earlier FT-IR PAS spectra have been presented by Vidrine (12). 

The technique employed is IR-FT photothermal beam deflection spectroscopy (PBDS). It is an off-shoot of photoacoustic spectroscopy (PAS) [1] and is based on the "mirage detection of the photothermal effect invented by Boccara et al. [2] and shown to result in a spectroscopic technique of remarkable versatility and utility. Some applications of "mirage spectroscopy," mainly in the visible, and theoretical treatments, have been described [3 6]. The method has now been developed for use in the IR. The spectrometer and techniques are described in detail elsewhere [7], but it will be useful to give a brief outline of the principles. 

ATR FT-IR spectroscopy has also been employed to monitor the solid-phase synthesis of substituted benzopyranoisoxazoles [180]. Finally, Huber et al. [181] have also reported that this technique is particularly suitable for the characterization of supported molecules in combinatorial chemistry, as well as for the identification of side products and for Photoacoustic (PA) FT-IR. 

PAS-FTIR spectroscopy measurements were carried out on the JIR-SI X200 FT-IR spectrometer (JEOL Co. Ltd. Japan) equipped with a MTEC 300 photoacoustic cell (MTEC... 

Routine methods of chemical analysis can be applied to water-based coatings. For example, the nature of the binder can be determined by infrared spectroscopy. Water-resistant plates, such as KRS5 or zinc selenide, must be used if capillary films are cast from the aqueous dispersion. Dried films can be analyzed by surface-sensitive techniques such as attenuated total reflection (ATR) or photoacoustic spectroscopy (PAS). Both these techniques require the use of Fomrier transform infrared (FT IR) instruments to obtain spectra in a reasonable time. 

Vibrational spectroscopy represents two physically different, yet complementary spectroscopic techniques IR and Raman spectroscopy. Although both methods have been utilised for many years, recent advances in electronics, computer technologies and sampling made Fourier transform infrared (FTIR) and Raman (FT-Raman) one of the most powerful and versatile analytical tools. Enhanced sensitivity and surface selectivity allows non-invasive, no-vacuum molecular level analysis of surface and interfaces. Emphasis is placed on recent advances in attenuated total reflectance (ATR), step-scan photoacoustic (SS-PA), Fourier transform infrared (FTIR) and FT-Raman microscopies, as utilised to the analysis of polymeric surfaces and interfaces. A combination of these probes allows detection of molecular level changes responsible for macroscopic changes in three dimensions from various depths. 7 refs. 

The other difficulty in the IR studies of carbons using halide pellets is the exposure of the carbon material to atmospheric gases and vapors that tend to vitriate the results. The development of elaborate techniques for obtaining carbonaceous films and preparation of charcoals by carbonization under vacuum conditions broadened the scope of applications of IR spectroscopy to the study of carbons and their surface groups. Furthermore, the sensitivity of IR measurements has been largely enhanced by using Fourier-Transform (FT), Photoacoustic (PAS), and Photothermal Beam Deflection (PDS) IR spectroscopy. 

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