Infra-red reflection-absorption

Both these concerns were addressed by the development of modified IR techniques. In the technique of Subtractively Normalised Fourier Transform IR Spectroscopy (SNIFTIRS) or Potential Difference IR (SPAIRS or PDIR) [37], the increased stability and sensitivity of Fourier Transform IR is exploited, allowing usable spectra to be obtained by simple subtraction and ratioing of spectra obtained at two potentials without the need for potential modulation or repeated stepping. A second technique which does not call for potential modulation, but actually modulates the polarisation direction of the incoming IR beam is termed Photo-elastically Modulated Infra-Red Reflectance Absorption Spectroscopy (PM-IRRAS) this was applied to the methanol chemisorption problem by Russell and co-workers [44], and Beden s assignments verified, including the potential-induced shift model for COads. 

SNIFTRS Subtractively Interfacial Fourier Transform Infra-Red Spectroscopy PM-FT-IRRAS Polarization Modulated Fourier Transform Infra-Red Reflection Absorption Spectroscopy... 

RAIRS reflection absorption infra red spectroscopy (see IRAS)... 

G8. Gould, J. H., Construction and use of reflecting multiple-pass absorption cells for the ultra-violet, visible and near-infra-red. Appl. Spectrose. 25, 103-105 (1971). 

Cholesteric liquids can rotate polarized light to a large degree, such as some thousand degrees per 1 mm layer thickness for visible light [258]. Because of different absorption of the two polarized components in the cholesteric liquid, the material shows dichroism. Most of the effects are applied practically. The colour change in reflection with temperature of a cholesteric liquid can be used for very sensitive temperature measurements of 0.001°C It is even possible to construct infra-red/visible image converters with cholesteric liquid crystals. 

Diffuse Reflectance Infra-Red Fourier Tranfform Spectroscopy. Spectra were acquired in situ using a DRIFT accessory (Collector) equipped with an environmental cell (Spectratech). DRIFT spectra were recorded in nitrogen up to about 500°C (to avoid absorption bands due to physisorbed or hydrogen-bridged water) on a Perkin Elmer 1600 FTIR spectrometer (64 scans, resolution 8 cm- ). 

In this context, dialdehyde la (5 mg, 0.017 mmol), sarcosine (14 mg, 0.157 mmol) and five-fold excess of Ceo (60 mg, 0.083 mmol) dissolved in 10 ml of o-dichlorobenzene (o-DCB) heated at 130 °C for 90 min. After a typical work up procedure, the reaction mixture is purified by recycling HPLC on a preparative Buckyprep Cosmosil column (250 X 20 mm, toluene eluent, lOml/min flow rate) to furnish bis-fullerene derivative 3 in 32 % yield. The bis-fullerene 3 shows moderate solubility, thus allowed us to record and NMR spectra (Supp. Info., Fig. SI) corroborating the depicted structure in Scheme 1. The attenuated-total-reflectance infra-red (ATR-IR) spectrum of 3 demonstrates the characteristic stretching vibrations of the C-H (2803-3030cm" ) as well as the characteristic absorptions for fullerenes (Supp. Info., Fig. S2). Matrix-assisted-laser-desorption time-of-flight mass-spectroscopy (MALDI-TOF-MS), in the negative ionization mode and with the aid of trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile shows the molecu-... 

Diffuse Reflectance Fourier Transform Infra Red Spectroscopy. Silica exhibits an absorption band at 3750 cm l caused by the stretching vibration of the free hydroxyl groups at the surface. When the surface is covered with active material, this absorption drops, thus providing information about the coverage of the silica surface [6], The catalysts were ground and mixed with potassium chloride (KG < 50 i.m, analytical grade). The thus obtained samples contained S.O wt% of the catalyst. The spectra were taken with a diffuse reflection cell installed in a Perkin Elmer 1600 spectrometer. The spectra were normalized at the symmetric Si-O-Si stretching vibration at t) = 805 cm 1. The area of the peak at 3750 cm was used to estimate the covered silica surface (%). 

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