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Title: Terahertz Microspectroscopy and Infrared Reflection-Absorption Spectroscopy Apparatuses at UVSOR-II

Abstract

We have recently constructed two specialized end stations, one is the terahertz microspectroscopy (THz-MS) and the other the infrared reflection-absorption spectroscopy (SR-IRAS). Both instruments have been tested using synchrotron radiation in the infrared and terahertz regions at UVSOR-II. The THz-MS station covers the wavenumber region of 15,000 -40 cm-1 with the spatial resolution as same as the wavelength. This apparatus is a powerful tool for the electrodynamics on strongly correlated materials at low temperatures and under high pressures and also for the molecular vibration imaging of living cells. On the other hand, the SR-IRAS station covers the IR range down to 300 cm-1 with a high accuracy. The change of Al-N stretching and pyramidalization modes at 423 and 460 cm-1, respectively, due to potassium doping in Alq3 molecules on an Ag surface was observed.

Authors:
; ;  [1];  [2]
  1. UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan)
  2. School of Physical Sciences, Graduate University for Advanced Studies, Okazaki 444-8585 (Japan)
Publication Date:
OSTI Identifier:
21052586
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436131; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ABSORPTION SPECTROSCOPY; ACCURACY; ELECTRODYNAMICS; IMAGES; INFRARED SPECTRA; PRESSURE RANGE MEGA PA 10-100; REFLECTION; SPATIAL RESOLUTION; SYNCHROTRON RADIATION; THZ RANGE; WAVELENGTHS

Citation Formats

Kimura, Shin-ichi, Sakurai, Yoko, Nakamura, Eiken, and Mizuno, Takafumi. Terahertz Microspectroscopy and Infrared Reflection-Absorption Spectroscopy Apparatuses at UVSOR-II. United States: N. p., 2007. Web. doi:10.1063/1.2436131.
Kimura, Shin-ichi, Sakurai, Yoko, Nakamura, Eiken, & Mizuno, Takafumi. Terahertz Microspectroscopy and Infrared Reflection-Absorption Spectroscopy Apparatuses at UVSOR-II. United States. doi:10.1063/1.2436131.
Kimura, Shin-ichi, Sakurai, Yoko, Nakamura, Eiken, and Mizuno, Takafumi. Fri . "Terahertz Microspectroscopy and Infrared Reflection-Absorption Spectroscopy Apparatuses at UVSOR-II". United States. doi:10.1063/1.2436131.
@article{osti_21052586,
title = {Terahertz Microspectroscopy and Infrared Reflection-Absorption Spectroscopy Apparatuses at UVSOR-II},
author = {Kimura, Shin-ichi and Sakurai, Yoko and Nakamura, Eiken and Mizuno, Takafumi},
abstractNote = {We have recently constructed two specialized end stations, one is the terahertz microspectroscopy (THz-MS) and the other the infrared reflection-absorption spectroscopy (SR-IRAS). Both instruments have been tested using synchrotron radiation in the infrared and terahertz regions at UVSOR-II. The THz-MS station covers the wavenumber region of 15,000 -40 cm-1 with the spatial resolution as same as the wavelength. This apparatus is a powerful tool for the electrodynamics on strongly correlated materials at low temperatures and under high pressures and also for the molecular vibration imaging of living cells. On the other hand, the SR-IRAS station covers the IR range down to 300 cm-1 with a high accuracy. The change of Al-N stretching and pyramidalization modes at 423 and 460 cm-1, respectively, due to potassium doping in Alq3 molecules on an Ag surface was observed.},
doi = {10.1063/1.2436131},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • Development of intense terahertz radiation source is progressing at UVSOR-II, based on the mechanism of coherent synchrotron radiation (CSR). The terahertz CSR has successfully been produced by two methods. When the storage ring is operated in the single bunch mode with a sufficiently high beam current, intense bursts of terahertz radiation are emitted. Micro-structures in the longitudinal density distribution of the electron bunches created by a beam instability may be the origin of the radiation. The duration of the bursts is typically 100 micro-seconds. The peak intensity is 10000 times higher than that of the normal synchrotron radiation. The burstsmore » appear chaotically or quasi-periodically depending on the beam current with a typical interval of 10 milli-seconds. It has been also demonstrated that the terahertz CSR could be produced by the laser-bunch slicing method. The density modulation produced on the electron bunch by the laser is the origin of CSR. The repetition rate of the terahertz pulses is 1 kHz, which is same as the laser repetition rate. The intensity per pulse is 105 times higher than that of the normal SR.« less
  • The infrared-terahertz beamline at UVSOR-II has been upgraded in 2004 for covering very low energy region below 0.3 THz (= 10 cm-). At the beamline, several characteristic experiments in the terahertz region are performed. Two examples of such experiments, reflectivity measurements at low temperatures and at high pressures are reported.
  • The adsorption of methanol on ordered epitaxial layers of cerium oxides grown on a Cu(111) substrate has been studied using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), temperature-programmed desorption (TPD), and Fourier transform reflection/absorption infrared spectroscopy (FT-RAIRS) measurements. The oxide films exhibit a LEED pattern characteristic of a CeO{sub 2}(111)-like structure, but the Ce/O stoichiometry achieved is strongly dependent on the exact pretreatment and film history. Grazing emission XPS also indicates that some Ce{sup 3+} ions are still present in the surface layers at 300 K after oxidation treatments. Methanol adsorbs dissociatively at 300 K, with a relatively highmore » sticking probability, to yield surface methoxy species. The IR spectra of the methoxy species, in particular the C-O stretch frequency, provide information about their coordination to the oxide surface, the presence of surface oxygen vacancies, and the general level of oxidation of the film. The methoxy species are stable on the (111)-type terraces of thicker (> 5 ML) oxide films to temperatures in excess of 550 K but then decompose at about 585 K to yield predominantly H{sub 2} and CO with some simultaneous evolution of formaldehyde and water. A substantial number of more coordinatively unsaturated cerium ions exist at and near the periphery of oxide islands on films of a submonolayer oxide coverage and on aggregated films of higher oxide coverage (between 1 and 5 ML). When the substrate is well-oxidized, then some of the methoxy species adsorbed at such sites are readily oxidized to the formate species while the decomposition temperature of the remaining methoxy groups in this peripheral region is lowered to about 560 K and their decomposition yields a higher proportion of formaldehyde than is seen for the (111) terrace sites.« less
  • The interaction of CO with MgO ultrathin films grown on a Mo(100) surface is studied using infrared reflection--absorption spectroscopy, temperature programmed thermal desorption (TPD), and x-ray photoelectron spectroscopy. CO adsorbed on 7 ML of MgO shows an infrared band at 2178 cm{sup {minus}1}. This blue-shift of the CO stretching frequency relative to that of CO in the gas phase (2143 cm{sup {minus}1}) is attributed to electron charge transfer from the CO 5{sigma} orbital to the MgO surface. It is further shown that CO adsorption induces a 0.4 eV shift in the Mg(2{ital p}) and O(1{ital s}) core levels of themore » MgO thin films to lower binding energy, consistent with the charge transfer from CO molecules to the MgO thin films. The TPD spectra indicate that CO molecules on the MgO thin films desorb in the 100--180 K sample temperature range. The CO adsorption heat on 7 ML of MgO is deduced to be 9.9 kcal/mol using an isothermal adsorption method.« less
  • Fourier transform infrared microspectroscopy (FTIRM) is a widely used method for mapping the material properties of bone and other mineralized tissues, including mineralization, crystallinity, carbonate substitution, and collagen cross-linking. This technique is traditionally performed in a transmission-based geometry, which requires the preparation of plastic-embedded thin sections, limiting its functionality. Here, we theoretically and empirically demonstrate the development of reflection-based FTIRM as an alternative to the widely adopted transmission-based FTIRM, which reduces specimen preparation time and broadens the range of specimens that can be imaged. In this study, mature mouse femurs were plastic-embedded and longitudinal sections were cut at a thicknessmore » of 4 {micro}m for transmission-based FTIRM measurements. The remaining bone blocks were polished for specular reflectance-based FTIRM measurements on regions immediately adjacent to the transmission sections. Kramers-Kronig analysis of the reflectance data yielded the dielectric response from which the absorption coefficients were directly determined. The reflectance-derived absorbance was validated empirically using the transmission spectra from the thin sections. The spectral assignments for mineralization, carbonate substitution, and collagen cross-linking were indistinguishable in transmission and reflection geometries, while the stoichiometric/nonstoichiometric apatite crystallinity parameter shifted from 1032/1021 cm{sup -1} in transmission-based to 1035/1025 cm{sup -1} in reflection-based data. This theoretical demonstration and empirical validation of reflection-based FTIRM eliminates the need for thin sections of bone and more readily facilitates direct correlations with other methods such as nanoindentation and quantitative backscatter electron imaging (qBSE) from the same specimen. It provides a unique framework for correlating bone's material and mechanical properties.« less