Showing papers on "Fourier transform infrared spectroscopy published in 1980"
01 Apr 1980
TL;DR: In this paper, the structure of γ-aminopropyltriethoxysilane (APS) has been studied in aqueous solution and as a solid using Fourier transform infrared spectroscopy.
Abstract: The structure of γ-aminopropyltriethoxysilane (APS) has been studied in aqueous solution and as a solid using Fourier transform infrared spectroscopy. The monomeric aminosilane forms an internal cyclic chelate structure when hydrolyzed. Two vibrational bands have been found near 1575 and 1600 cm −1 in condensed aminopropylsiloxane polymer. The band at 1575 cm −1 is assigned to the NH 2 deformation mode of the acceptor amine groups involved in strong hydrogen bonding and the band at 1600 cm −1 is assigned to the NH 2 groups. Heat treatment causes the formation of nonring chain-structured aminosilanes. In the study of the structure of APS coupling agent on high-surface-area silica gel (Cab-O-Sil) and E-glass fibers, it was found that the aminosilane adsorbed on silica as essentially a monolayer and the amino group chemically interacted with the glass surface. The adsorbed APS on E-glass fiber exists as a multilayer, and formed a predominately cyclic ring structure in the coupling agent interphase.
395 citations
TL;DR: It is concluded that in the gel phase, at all temperatures below the main transition, the acyl chains are predominantly in all-trans conformations and that the temperature-dependent variations of spectral parameters result from changes in interchain interactions.
Abstract: Fourier transform infrared spectroscopy has been used to study the infrared-active acyl chain vibrational modes of fully hydrated multibilayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (L-DPPC) over the temperature range 0-55 degrees C. Frequencies, bandwidths, and other spectral parameters were measured as a function of temperature for the methylene scissoring, rocking, and wagging modes, as well as for the C-H stretching modes, and they were used to monitor the packing of the acyl chains. Particular emphasis was placed on determining the nature of the pretransition event. It is shown that between 36 and 38 degrees C the spectral changes are indicative of a phase change in the acyl chain packing from an orthorhombid to a hexagonal subcell. It is also concluded that in the gel phase, at all temperatures below the main transition, the acyl chains are predominantly in all-trans conformations and that the temperature-dependent variations of spectral parameters result from changes in interchain interactions.
235 citations
212 citations
TL;DR: In this paper, diffuse reflectance techniques enable increased sensitivity to be obtained for infrared micro-sampling compared with the use of KBr micropellets, when nonabsorbing matrices such as KCl are used, detection limits of less than 10 ng of samples are observed.
Abstract: It is shown that diffuse reflectance techniques enable increased sensitivity to be obtained for infrared microsampling compared with the use of KBr micropellets. When nonabsorbing matrices, such as KCl, are used, detection limits of less than 10 ng of samples are observed. Samples absorbed on graphitized substrates, which have a fairly strong general absorption but few intense absorption bands, may also be studied but at somewhat reduced sensitivity. Diffuse reflectance infrared Fourier transform spectrometry does not appear to be particularly useful for studying adsorbates on silica gel, which is not only a strong infrared absorber but also has a surface which is so active that small changes in the surface structure can change the spectrum significantly. Extraction of sample spots from thin layer chromatography plates followed by deposition onto KCl yields much better results than in situ measurements.
148 citations
142 citations
TL;DR: In this article, the advantages and disadvantages of photoacoustic detection are discussed, and comparisons of sample spectra obtained by different techniques, including photoacoustical detection, are presented and compared.
Abstract: Fourier transform infrared spectroscopy of solids and liquids using photoacoustic detection is reported here. The advantages and disadvantages of photoacoustic detection are discussed, and comparisons of sample spectra obtained by different techniques, including photoacoustic detection, are presented and compared. Photoacoustic Fourier transform infrared spectroscopy is a promising spectroscopic method for IR analysis in cases where sample preparation is difficult.
131 citations
TL;DR: Fourier transform infrared spectroscopy is applied to the study of intact and deproteinated plasma membranes of Acholeplasma laidlawii, enriched biosynthetically with perdeuteriopalmitoyl chains to show the effects of protein on the phase transition.
Abstract: Fourier transform infrared spectroscopy is applied to the study of intact and deproteinated plasma membranes of Acholeplasma laidlawii, enriched biosynthetically with perdeuteriopalmitoyl chains. The temperature-dependent behavior is monitored via the CD stretching modes and compared with that observed in the model membrane 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine. The broad ramplike transition observed in the natural membranes is shown to consist of two overlapping stages. In the lower temperature range the principal change is a reduction in the rigidity of the lipid matrix. Subsequently, over a 5 degrees C range, centered at the growth temperature, a large change in the gauche/trans conformer ratio of the acyl chains occurs, similar to that generally observed in model systems. This is followed by an abrupt cessation of the phase transition. The effects of membrane protein on the phase transition are shown to be relatively minor. Firstly, they produce a decrease in the rate of acyl chain motion at a given temperature, resulting in a reduction in the width of the transition. In addition, the presence of protein increases the population of gauche conformers of the fatty acyl chains in the liquid-crystalline phase of the membrane lipids.
128 citations
TL;DR: In this article, Fourier transform infrared spectroscopy was applied to a quantitative analysis of the low-temperature ash from ten consecutive channel samples along an exploration adit through a high-volatile coking coal seam.
113 citations
TL;DR: In this paper, low-pressure, Doppler-limited absorption spectra of 16O12C16O, 16O13C 16O, 1516C17O, 1416C18O, and 16O15C16E have been recorded in the 4.3-μm region with a high-information Fourier transform interferometer operating in a vacuum.
104 citations
TL;DR: The infrared spectrum of dihydroxyacetone phosphate bound to triosephosphate isomerase has been measured, providing direct evidence of enzyme-induced distortion of the substrate.
Abstract: The infrared spectrum of dihydroxyacetone phosphate bound to triosephosphate isomerase has been measured. There are two carbonyl bands corresponding to the bound substrate, with an intensity ratio of about 3:1. Relative to the carbonyl absorption of dihydroxyacetone phosphate in free solution, the major band is shifted by 19 cm-1 to 1713 cm-1, providing direct evidence of enzyme-induced distortion of the substrate. This strain is probably attributable to an enzymic electrophile that polarizes the carbonyl group of the substrate and thereby promotes catalysis.
100 citations
TL;DR: In this paper, the structural changes of a vinyl functional silane coupling agent on E-glass fibers, induced during the immersion test in hot water, have been studied using Fourier transform infrared spectroscopy.
Abstract: Molecular structural changes of a vinyl functional silane coupling agent on E-glass fibers, induced during the immersion test in hot water, have been studied using Fourier transform infrared spectroscopy. The amount of the coupling agent on the glass fibers is reduced by hydrolytic degradation. Silanol groups formed by the hydrolysis of the siloxane groups have been detected in the FT-IR difference spectrum in the range 930–840 cm−1 due to the SiO stretching mode of the SiOH groups. Heat treatment produces partial reformation of the siloxane bonds.
TL;DR: Polarized Fourier transform infrared spectroscopy and far ultraviolet circular dichroism of oriented multilamellar films of photoreceptor membranes indicate rhodopsin alpha-helices are predominantly oriented perpendicular to the bilayer plane.
TL;DR: Fourier Transform infrared analysis has been examined as a technique for evaluating the oil-yielding potential of raw oil shales The technique was developed recently for analysing coals, and gives a quantitative measure of aliphatic, aromatic and hydroxyl hydrogen.
TL;DR: The sensitivity of gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR) may be improved by use of small bore gold-coated glass gas cells.
Abstract: The sensitivity of gas chromatography/Fourier transform infrared spectroscopy (GC/FT-IR) may be significantly improved by use of small bore gold-coated glass gas cells. This note describes the method of preparing internally gold-coated glass or quartz tubes for GC-IR applications.
TL;DR: In this article, a wide selection of infrared absorption spectra of opaque samples is presented to show the versatility of Fourier-transformed infrared photoacoustic spectroscopy, and a method for correcting these spectra for incident radiant power variations with respect to wavelength is also demonstrated.
Abstract: A wide selection of infrared absorption spectra of opaque samples is presented to show the versatility of Fourier-transformed infrared photoacoustic spectroscopy. A method for correcting these spectra for incident radiant power variations with respect to wavelength is also demonstrated.
TL;DR: In this paper, the vibration-rotation emission spectrum of the nitric oxide molecule has been recorded with a high-resolution Fourier transform interferometer (resolution 10 −2 cm −1 ) in the spectral range 2900 − 3810 cm − 1.
TL;DR: In this article, the authors present the state-of-the-art of FTIR spectroscopy in the characterization of polymeric structure, which they call FTIR-VQA.
TL;DR: The Fourier transform infrared evolved gas analysis (FT-IR-EGA) as mentioned in this paper has been used in a number of applications, such as comparison of different materials, comparison of materials before and after modification and examination of oxygen-induced effects relative to pyrolysis effects.
Abstract: Thermal analysis plays an important role in the evaluation and development of many complex chemical systems. Often combustion data as well as pyrolytic data on these systems may be important. Analytical techniques are required which maximize the amount of useful information which can be obtained per thermal experiment. Fourier transform infrared spectral analysis of gases evolving from materials vs temperature can provide information on both pyrolysis and combustion processes, and an apparatus for performing such analysis routinely is described. While the Fourier transform infrared evolved gas analysis (FT-IR-EGA) system has numerous applications, three applications using tobacco as a sample are presented for illustration. These include comparison of different materials, comparison of materials before and after modification and examination of oxygen-induced effects relative to pyrolysis effects. The FT-IR-EGA technique should prove to be a useful tool in elucidating thermal processes in complex systems.
TL;DR: In this article, the Fourier transform infrared spectroscopy (FT i.s.r) was used to measure free radicals and new chemical species formed during mechanical deformation and fracture.
TL;DR: The results of experiments designed to study the infrared spectra of transient species produced by ultraviolet photolysis of acetaldehyde are reported and analyzed in this article, and the consequences of poor control are described and a qualitative explanation is offered.
Abstract: The results of experiments designed to study the infrared spectra of transient species produced by ultraviolet photolysis of acetaldehyde are reported and analyzed. Spectra obtained in similar work [A. W. Mantz, Appl. Opt. 17, 1347 (1978)] are critically reinterpreted. The evidence presented demonstrates that insufficient attention has been given to the necessary stringent control of experimental conditions. The consequences of poor control are described and a qualitative explanation is offered. This paper discusses, in particular, the production of spectral artifacts consisting of displaced (not folded) bands and their previous erroneous assignments. Other practical aspects of time resolved Fourier transform spectroscopy with a rapid scanning Michelson interferometer are outlined.
IBM1
TL;DR: In this paper, Fourier transform infrared spectroscopy has been used in conjunction with differential scanning calorimetric measurements to investigate the nature of molecular degradation and its effect on the phase transition temperatures in irradiated polytetrafluoroethylene (PTFE).
Abstract: Fourier transform infrared spectroscopy has been used in conjunction with differential scanning calorimetric measurements to investigate the nature of molecular degradation and its effect on the phase transition temperatures in irradiated polytetrafluoroethylene (PTFE). Both the 19 and 30/sup 0/C transitions are observed to exhibit similar shifts to low temperatures upon irradiation. Infrared absorbance subtraction data from irradiated PTFE indicate a continual decrease in sample crystallinity accompanied by an increase in the number of free and bonded - COOH groups with increasing dose consistent with molecular degradation by chain scission. By comparing infrared band intensities on a number of irradiated PTFE samples with those from short chain perfluoro n-alkanes, it was determined that the overall reduction in chain length caused by irradiation was primarily responsible for the observed reduction in both phase transition temperatures.
TL;DR: A Perkin-Elmer infrared Data Station associated with a simple IR spectrometer is shown to give excellent results with aqueous model and biomembrane systems and the potential for studying intrinsic protein conformations is emphasised.
TL;DR: The pure rotational spectrum of a mixture of H 2 16 O, H 2 17 O and H 2 18 O between 50 and 730 cm −1 was recorded on the Fourier transform spectrometer at the University of Oulu.
TL;DR: In this paper, a method for determining net and total shallow impurity concentrations in s silicon by low temperature IR measurements was developed, and calibration factors for quantitative analysis of boron, phosphorus and arsenic were experimentally determined, and estimates for the other shallow impurities were made.
TL;DR: Both R state and T state quaternary structures stress the a chain tertiary structure relative to isolated (“unstressed”) chains.
TL;DR: In this article, a Michelson interferometer with step-and-integrate mirror motion is described for use in Fourier transform photoacoustic spectrometry (FTPAS) at visible wavelengths.
Abstract: A Michelson interferometer with step‐and‐integrate mirror motion is described for use in Fourier transform photoacoustic spectrometry (FTPAS) at visible wavelengths. An overview of mechanical and software construction is supplied and the advantages of FTPAS are illustrated with a spectrum of powdered erbium oxide at visible wavelengths. The relative merits of step‐and‐integrate and rapid scan mirror motion for FTPAS are considered.
TL;DR: Fourier transform photoacoustic spectroscopy (FTPAS) can be carried out in the visible using either a piezoelectric crystal or a microphone to detect the interferogram produced in a sample when the latter is illuminated by white light passed through a Michelson interferometer as discussed by the authors.
Abstract: Fourier transform photoacoustic spectroscopy (FTPAS) can be carried out in the visible using either a piezoelectric crystal or a microphone to detect the interferogram produced in a sample when the latter is illuminated by white light passed through a Michelson interferometer. Spectra of lanthanide oxides and whole human blood are reported that illustrate benefits and limitations of visible FTPAS.
TL;DR: In this article, a fast scanning Fourier Transform Infrared Spectroscopy (FTIR) was applied to obtain spectra from aluminium anodic coatings, which were recorded with different measuring techniques e.g. transmission, absorption-reflection and ATR in the far and middle IR regions.