IR synchrotron radiation

In this chapter we will try to illustrate what is meant by an IR synchrotron radiation beamline and to discuss the major advantages of these instruments for the research examples described in this chapter and in the other chapters of the book. 

Figure 3.7 The linear polarization degree Pl of the IR synchrotron radiation at the sample site measured at DAONE in the far-IR region. The inset shows a comparison between ray-tracing simulation results and experimental data. [Reprinted from ref. 24.]...

In this chapter we consider developments in the use of infrared (IR) synchrotron radiation for microspectroscopy based on instruments having two-dimensional (2D) array detectors. As with microspectroscopy using singleelement detectors (SEDs), we anticipate that the IR synchrotron radiation source is likely to play a significant role in the field of biological and biomedical spectroscopy. That role is not as a replacement for the standard thermal source, but as a complement where the synchrotron source is used to address problems on a local scale in combination with larger area surveys conducted using the standard IR source. 

The characteristics of IR synchrotron radiation have been discussed by numerous authors and in Chapter 3 of this volume. Rather than cover all of the details of such sources, our intent is to describe primarily the features relevant to multi-element imaging systems and techniques. The reader interested in a... 

Resonant y-ray absorption is directly connected with nuclear resonance fluorescence. This is the re-emission of a (second) y-ray from the excited state of the absorber nucleus after resonance absorption. The transition back to the ground state occurs with the same mean lifetime t by the emission of a y-ray in an arbitrary direction, or by energy transfer from the nucleus to the K-shell via internal conversion and the ejection of conversion electrons (see footnote 1). Nuclear resonance fluorescence was the basis for the experiments that finally led to R. L. Mossbauer s discovery of nuclear y-resonance in ir ([1-3] in Chap. 1) and is the basis of Mossbauer experiments with synchrotron radiation which can be used instead of y-radiation from classical sources (see Chap. 9). 

NIS of synchrotron radiation yields details of the dynamics of Mossbauer nuclei, while conventional MS yields only limited information in this respect (comprised in the Lamb-Mossbauer factor /). NIS shows some similarity with Resonance Raman- and IR-spectroscopy. The major difference is that, instead of an electronic resonance (Raman and IR), a nuclear resonance is employed (NIS). NIS is site-selective, i.e., only those molecular vibrations that contribute to the overall... 

Although a number of secondary minerals have been predicted to form in weathered CCB materials, few have been positively identified by physical characterization methods. Secondary phases in CCB materials may be difficult or impossible to characterize due to their low abundance and small particle size. Conventional mineral identification methods such as X-ray diffraction (XRD) analysis fail to identify secondary phases that are less than 1-5% by weight of the CCB or are X-ray amorphous. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM), coupled with energy dispersive spectroscopy (EDS), can often identify phases not seen by XRD. Additional analytical methods used to characterize trace secondary phases include infrared (IR) spectroscopy, electron microprobe (EMP) analysis, differential thermal analysis (DTA), and various synchrotron radiation techniques (e.g., micro-XRD, X-ray absorption near-eidge spectroscopy [XANES], X-ray absorption fine-structure [XAFSJ). 

IR, Raman, NMR, ESR, UPS, XPS, AES, EELS, SIMS) [1]. However, some industrial carbon materials such as amorphous carbon films and carbon black cannot be easily characterized from the local-structure point of view by these methods, because these materials usually take amorphous and complex structures. Recently, soft X-ray emission and absorption spectroscopy using highly brilliant synchrotron radiation [2] has been utilized to characterize various carbon materials, because information on both the occupied and unoccupied orbitals, which directly reflect the local structure and chemical states, can be provided from the high-resolution soft X-ray measurements. We have applied the soft X-ray spectroscopy to elucidate the local structure and chemical states of various carbon materials [3]. Additionally, we have successfully used the discrete variational (DV)-Xa method [4] for the soft X-ray spectroscopic analysis of the carbon materials, because the DV-Xa method can easily treat complex carbon cluster models, which should be considered for the structural analysis of amorphous carbon materials. 

EXAFS data (Rh K-edge ((23220 eV) or Ir Lm-edge (13419 eV)) were collected in transmission mode on station 9.2 of the Daresbury Synchrotron Radiation Source, operating at 2 GeV with an average current of 150 mA. A water-cooled Si(220) double crystal monochromator was used, with its angle calibrated by running an edge scan of a 5 pm Rh or Ir foil. For each sample 2-10 scans were recorded at room temperature in the... 

The IR spectra were recorded at ambient temperature (if not expressly stated otherwise) on a Fourier transform spectrometer DIGILAB FTS 20E with resolutions between 1 and 4 cnf . The EXAFS and XANES data were obtained at the Cu K edge on the E4 and X beam lines at the synchrotron radiation source of HASYLAB/DESY in Hamburg, at a ring energy of 5.3 GeV with a resolution of... 

Hirschmugl CJ (1994) Low frequency adsorbate substrate dynamics for CO/Cu studied with infrared synchrotron radiation. PhD Dissertation, Yale University, New Haven, CT Hirschmugl CJ, Williams GP (1995) Signal-to-noise improvements with a new far-IR rapid-scan Michelson interferometer. Rev Sci Inst 66 1487-1488... 

APD = avalanche photodiode detector APS = advanced photon source DFT = density functional theory ESRF = European synchrotron radiation facility HOPE = high-density polyethylene IR = infrared INS = inelastic neutron scattering KED = kinetic energy distribution Mb = myoglobin NIS = nuclear inelastic scattering NRVS = nuclear resonance vibrational spectroscopy NRIXS = nuclear resonant inelastic X-ray scattering OEP = octaethylporphyrin sGC = soluble guanylate cyclase VDOS = vibrational density of states. 

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