Fourier transform spectroscopy

About: Fourier transform spectroscopy is a research topic. Over the lifetime, 5418 publications have been published within this topic receiving 134133 citations.

Hydrogen−Deuterium Exchange of Streptavidin and Its Complex with Biotin Studied by 2D-Attenuated Total Reflection Fourier Transform Infrared Spectroscopy

Abstract: Hydrogen−deuterium exchange for streptavidin and its complex with biotin is studied by means of attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. To analyze the spectral changes upon deuteration, difference spectra and two-dimensional correlation spectra are calculated. We find that the exchange rate varies with the secondary structure in which the exchanging amide protons are incorporated. The most slowly exchanging protons, with a characteristic time constant on the order of hours, are part of the β-sheet secondary structure. The separation in time of exchange of the β-sheet from other structural elements allows the amide II and II‘ frequencies of the β-sheet (1530 and 1445 cm-1) to be identified. A second component which exchanges more rapidly than the β-sheet is characterized by its amide I frequencies 1680, 1640, and 1465 cm-1. This component is attributed to the exchange of amide groups in secondary structures other than the central β-barrel. Binding of the ligand res...

Structural states of natural potassium feldspar: An infrared spectroscopic study

Abstract: Natural samples of K-feldspar representing various states of Al, Si order were characterised using X-ray methods, transmission electron microscopy, and Fourier transform infrared spectroscopy. Line profiles of infrared absorption bands were observed to show strong correlation with the degree of Al, Si order present. In particular, the absorption frequencies of the 540 cm−1 and 640 cm−1 bands were seen to vary by ca. 10 cm−1 between sanidine and microcline, with modulated samples respresenting intermediate behaviour. Linewidths of these modes also decrease by ca. 50% in this series. The experimental results are discussed within the framework of Hard Mode Infrared Spectroscopy (HMIS), and it is shown that the absorption frequencies vary with the short range order parameter τ = (4t1-1)2 and the symmetry breaking order parameter describing Al, Si order, Q od=(t1 0−t1 m)/Q od=(t1 0+t1 m), where t1 is the average Al occupancy on the T1 sites and t1 o and t1 m are the individual site occupancies of the T1 o and T1 m sites, respectively. The structural state of orthoclase is characterised by strain-induced modulations with large spatial variations of the modulation wavelength. No such modulations were observed in the degree of local Al, Si order. Sanidine shows mode hardening in excess of the extrapolated effect of symmetry breaking Al, Si order, which is presumably related to nonsymmetry breaking ordering between T1 and T2 sites and/or as yet unobserved short range order of the symmetry breaking ordering scheme. The possibility of an additional phase transition in K-feldspar at temperatures above 1300 K is discussed.

Fourier transform–electron paramagnetic resonance spectroscopy of correlated radical pairs

Abstract: Utilizing the high time and phase resolution of Fourier transform electron paramagnetic resonance, the buildup and decay kinetics of the transient radical pair Zn tetraphenylporphyrin+/Duroquinone− in ethanol could be studied by detecting the dispersive component in the Fourier transformed free induction decays of the fully separated radical anions. The dispersive line components originate from the exchange coupling J of the radical pair in its metastable state trapped by an attractive temperature dependent Coulomb interaction U(rc,T) at an equilibrium distance rc. The decay rate constant kd into free ions was studied over the temperature range of 225–298 K and varied from kd=3.2×106 to 10×106 s−1. This change in kd could be fully rationalized in terms of the temperature dependence of the solvent dielectric constant (leading to a variation of the cage potential from 0.07 to 0.12 eV) and the diffusion constant. The buildup rate constants were consistent with the assumption of a diffusion‐controlled electro...

Rapid Scan Infrared Fourier Transform Spectroscopy

Abstract: The characteristic asorption, reflection, or emission of particu lar frequencies of IR radiation has been used extensively over the last two decades to identify compounds and mixtures and to investigate intermolecular and intramolecular interactions. It is probably true to say that IR spectroscopy is the most widely used instrumental technique in analytical chemistry today. This is due to a variety of reasons, including the ease of operation of many IR spectrometers, the ease in which a sample may be classified according to its chemical class from its IR spectrum, the variety of states in which a compound may be investigated, the availability of libraries of IR spectra for the unique identification of a sample, and the accuracy to which quantitative analysis may be carried out.

Fourier transform spectroscopy in the visible and ultraviolet range

Abstract: In cases where the photon noise is the limiting factor, the multiplex gain is not always conserved; however the throughput (Jacquinot's advantage) is not affected. Therefore extension of Fourier transform spectroscopy to higher frequencies has great possibilities. Studies at high resolution, both in emission and in absorption, show that the performance achieved by Fourier transform spectroscopy in the visible and uv range is comparable with that reached in the ir.