Infrared spectroscopy during heating

The deterrnination of surface temperature and temperature patterns can be made noninvasively using infrared pyrometers (91) or infrared cameras (92) (see Infrared technology and raman spectroscopy). Such cameras have been bulky and expensive. A practical portable camera has become available for monitoring surface temperatures (93). An appropriately designed window, transparent to infrared radiation but reflecting microwaves, as well as appropriate optics, is needed for this measurement to be carried out during heating (see Temperature measurement). 

In order to get the pore system of zeolites available for adsorption and catalysis the template molecules have to be removed. This is generally done by calcination in air at temperatures up to 500 °C. A careful study (ref. 12) of the calcination of as-synthesized TPA-containing MFI-type single crystals by infrared spectroscopy and visible light microscopy showed that quat decomposition sets in around 350 °C. Sometimes special techniques are required, e.g. heating in an ammonia atmosphere (ref. 13) in the case of B-MFI (boron instead of aluminum present) to prevent loss of crystallinity of the zeolite during template quat removal. 

Figures 8.2 and 8.3 show stacked curves obtained by TG-Fourier transform infrared spectroscopy (FTIR) of KL measured in air and nitrogen. TG-FTIR measurements were carried out using a Seiko TG 220 themogravimeter equipped with a JASCO FTIR7000 spectrometer [44,45,49,50]. Sample mass was 10 mg and heating rate was 200°C/min. Airflow rate was controlled at 100 mL/min. The gases evolved during the thermal degradation of KL were simultaneously analyzed by FTIR. Spectra were recorded at 30-second intervals each spectrum is the average of 10 one-second scans. The spectral resolution was 1 cm...

In situ infrared spectroscopy of the precursor polymer during conversion (heated cell) confirms loss of the xanthate group in this step-wise fashion. The C-O-C symmetric stretch diminishes rapidly at -125 C. The asymmetric CH2 stretch in CH2-S (2924 cm ) and the symmetric CH2 stretch... 

In situ infrared spectroscopy (heated cell) and TGA-IR (evolved gas product analysis) are important tools that have been used to characterize the thermal elimination reaction in the synthesis of PPV and PPV derivatives using the precursor route. A detailed understanding of the reaction is important as the conditions of the reaction influence the properties of the resultant polymer product. The mechanism of the thermal elimination reaction can be characterized using in situ spectroscopy. Both an El and an E2 mechanism appears to be operating during the thermal conversion of PPV... 

The first type of semiconductor bolometer to come into use was the thermistor developed during World War II at Bell Laboratories to provide a simple, reliable but sensitive detector for use both in the then rapidly developing science of infrared spectroscopy and for heat sensing applications. The thermistor bolometer is still one of the most widely used of infrared detectors, although it has been replaced by more sensitive devices for the more demanding applications. 

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