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Now showing items 1 - 5 of 5

  • AIP Conference Proceedings [AIP XXII INTERNATIONAL CONFERENCE ON RAMAN SPECTROSCOPY - Boston (MA) (8–10 August 2010)] - Composition Of Aerosols From The Shelter Of The Chernobyl Power Plant

    Darchuk, L.   Worobiec, A.   Khan, V.   Krasnov, V.   Van Grieken, R.   Champion, P. M.   Ziegler, L. D.  

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  • Damage and molecular changes under a laser beam in SEM-EDX/MRS interface: a case study on iron-rich particles

    Worobiec, A.   Darchuk, L.   Brooker, A.   Potgieter, H.   Van Grieken, R.  

    The control of damage to individual environmental particles by a laser beam during Raman spectroscopy carried out in ambient air is generally well understood. The nature and control of damage under vacuum conditions (e. g. in the scanning electron microscopy with energy X-ray detection combined with micro-Raman spectroscopy - interfaced SEM-EDX/MRS) are more complex and less well comprehended. The physical and chemical processes that affect the damage caused to small particles by lasers still remain somewhat unclear, but certainly the atmosphere (vacuum/air) and the beam intensity have very significant influences. Furthermore, it has been determined that some particles (e. g. haematite), although stable under an electron beam, are damaged by the laser beam, hampering their analysis. Additionally, when simultaneous analyses by SEM/EDX and MRS are considered, the correct choice of the collection surface plays a crucial role. As a result, the following collection substrates were tested to determine their influence on the laser beam damage process to the particle: silver and aluminium foils and silicon wafers. A test study was performed using artificial examples of haematite (Fe(2)O(3)) particles. Exposure of Fe(2)O(3) particles in vacuum to 514- and 785-nm laser radiation often leads to their melting, transformation and evaporation. The dependence of the damage caused by the laser beam on the particle structure is reported here. Molecular and crystallographic changes have also been revealed. Formation of magnetite (as an effect of re-crystallisation) and Raman inactive structures was detected. Copyright (C) 2010 John Wiley & Sons, Ltd.
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  • Size distribution and chemical properties of welding fumes of inhalable particles

    Oprya, M.   Kiro, S.   Worobiec, A.   Horemans, B.   Darchuk, L.   Novakovic, V.   Ennan, A.   Van Grieken, R.  

    The goal of the present study was to analyze the relationship between the fume formation rate, welding conditions, chemical composition of welding fume particles and their size. In the range from 0.25 to 16 mu m aerodynamic diameter, three distinct types of welding fume particles were identified in the welder's breathing zone. The elemental composition of each type depended completely on the used welding materials, and reflects their mechanism of formation. Their relative abundance in the welding fume appeared to be dependent on the electrode coating, as well as the heat input during welding. (C) 2011 Elsevier Ltd. All rights reserved.
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  • Behavior of Semi-volatile Particles under a Laser and Electron Beam - Influence on the Quality of Analytical Results

    Worobiec, A.   Potgieter-Vermaak, S.   Darchuk, L.   Vishnyakov, V.   Potgieter, H.   Van Grieken, R.  

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  • Composition of prehistoric rock-painting pigments from Egypt (Gilf Kebir area)

    Darchuk, L.   Rotondo, G. Gatto   Swaenen, M.   Worobiec, A.   Tsybrii, Z.   Makarovska, Y.   Van Grieken, R.  

    The composition of rock-painting pigments from Egypt (Gilf Kebia area) has been analyzed by means of molecular spectroscopy such as Fourier transform infrared and micro-Raman spectroscopy and scanning electron microscopy coupled to an energy dispersive X-ray spectrometer and X-ray fluorescence analysis. Red and yellow pigments were recognized as red and yellow ochre with additional rutile. (C) 2011 Elsevier B.V. All rights reserved.
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