Samples photoacoustic Fourier transform

DW Vidrine. Photoacoustic Fourier transform infrared spectroscopy of solid samples. Appl Spectrosc 34 314-319, 1980. 

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. 

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. 

Infrared microscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and photoacoustic spectroscopy (PAS) techniques may be suitable for some types of sample but the use of... 

Gillette PC, Lando JB, Koening JL (1985) A survey of infrared spectral data processing techniques In Ferraro JR, Basile LJ (eds) Fourier transform infrared spectroscopy -applications to chemical systems, Vol 4 Academic Press, New York, 1-47 Graham JA, Grim WM III, Fateley WG (1985) Fourier transform infrared photoacoustic spectroscopy of condensed-phase samples, In Ferraro JR, Basile LJ (eds) Fourier transform infrared) spectroscopy - applications to chemical systems, Vol 4 Academic Press, New York, 345-392... 

Graham. J. A., Grim, N. M. and Fately, W. G. (1985). Fourier Transform infrared photoacoustic spectroscopy of condensed-phase samples. In Fouriertransform infrared spectroscopy Vol. 4 (ed. J. R. Ferraro and L. J. Basil), pp. 345-92. Academic Press, New York. [129]... 

It would be most desirable to study lipid oxidation in intact food products without the extraction or sample preparation steps currently necessary (e.g., pelletization, freeze-drying). Perhaps improvements in techniques such as the Fourier transform infrared photoacoustic spectroscopy (Yang and Irudayaraj, 2000) will open such possibilities. 

Applications of visible/UV Fourier transform spectroscopy will continue to include those topics already mentioned. Additional areas of expansion will probably include amplitude spectroscopy5 55 which has proved useful in the past by providing both absorption magnitude and phase information on transmitting samples, photoacoustic spectroscopy which can determine the composition of opaque samples, time-resolved chemical kinetic studies, and optical probing of combustion processes. 

Jiang EY (1999) Heterogeneity smdies of a single particle/ fibre by using Fourier transform infrared micro-sampling photoacoustic spectroscopy. Applied Spectroscopy 53 583-587. 

ABSTRACT. The construction and operation of a Michelson interferometer that permits Fourier transform photoacoustic spectroscopy of opaque and partially transparent samples at visible wavelengths is described. Multiplexing and throughput advantages are considered. A visible spectrum of Nd(III) doped laser glass is reproduced and potential kinetic applications are described. 

Gardalla and Grobe compared attenuated total reflectance and photoacoustic sampling for surface analysis of polymer mixtures by Fourier transform infrared spectroscopy. They show that analysis by attenuated total reflectance is more suitable for smooth surfaces and is faster. Photoacoustic methods have shallower sampling depths than attenuated total reflectance but the latter technique is applicable over a range that is more controllable. 

In Chapters 2 to 8 we describe the theory and instrumentation needed for an appreciation of the way that Fourier transform infrared and Raman spectra are measured today. The sampling techniques for and applications of FT-Raman spectrometry are described in Chapter 18. The remaining chapters cover the techniques and applications of absorption, reflection, emission, and photoacoustic spectrometry in the mid- and near-infrared spectral regions. 

In Chapter 20 we saw how photoacoustic (PA) spectra could be measured with a step-scan interferometer no matter whether the PA signal was demodulated with a lock-in amplifier or by digital signal processing (DSP). For DSP, a Fourier transform (FT) has the same function as the lock-in amplifier. Manning et al. [14] showed that the same approach is feasible in DIRLD spectrometry with a step-scan FT-IR spectrometer but without a PEM. Consider the case where the detector signal contains components caused by simultaneous sinusoidal phase modulation at frequency /pm, and sample modulation at frequency fs. The phase- and sample-modulated components of the signal can be demodulated either with a... 

Uotila, J. and Kauppinen, J. (2008) Fourier transform infrared measurement of solid-, liquid-, and gas-phase samples with a single photoacoustic cell. Appl. Spectrosc., 62, 655-660. 

See also Fibre Optic Probes in Optical Spectroscopy Clinical Applications Fourier Transformation and Sampling Theory Light Sources and Optics Photoacoustic Spectroscopy, Applications Photoacoustic Spectroscopy, Theory Scanning Probe Microscopes Scanning Probe Microscopy, Applications Scanning Probe Microscopy, Theory Surface Plas-mon Resonance, Applications Surface Plasmon Resonance, Theory. 

See also ATR and Reflectance IR Spectroscopy, Applications Fourier Transformation and Sampling Theory IR Spectrometers IR Spectroscopy, Theory Matrix Isolation Studied By IR and Raman Spectroscopies Photoacoustic Spectroscopy, Applications Photoacoustic Spectroscopy, Theory Quantitative Analysis Surface Studies By IR Spectroscopy. 

With the advent of the commercial FT-IR instruments, and computer techniques, it is now possible to record the infrared spectrum of almost any material regardless of its shape or form. A number of different sampling accessories are available for recording the infrared spectra. Some of these accessories such as AIR and specular reflectance have been used successfully with dispersive instruments, but the FT-IR instruments allow these accessories to be used more rapidly and with greater sensitivity. Most of the sample handling techniques have been reviewed in detail in the series of volumes on "Fourier Transform Infrared Spectroscopy" edited by J.R. Ferraro and J.R. Basile (1). In this paper, some of these techniques will be reviewed with particular emphasis on reflectance techniques (ATR and diffuse) and photoacoustic spectroscopy. Further applications such as far-IR, diamond cell, the absorption subtraction methodology can be found in the article by Krishnan and Ferraro (2). 

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