August 2010 Archives

Determination of the selenium content of soils is an important issue from the viewpoint of environmental and earth sciences. The work presents a lot of technical difficulties due to low concentrations within complex matrices. Dr. E. Margui (Institute of Earth Sciences "Jaume Almera", CSIC, Spain) and her colleagues have recently explored the possibilities of several analytical approaches combined with total reflection X-ray (TXRF) spectrometry. While direct analysis of a solid suspension has a relatively poor detection limit of around 1 mg/kg, a dispersive liquid-liquid microextraction procedure (DLLME) before the TXRF analysis of the soil digest provides much greater detection power. The detection limit is 0.05 mg/kg, which is comparable to or lower than previously published results. For more information, see the paper, "Analytical Possibilities of Total Reflection X-ray Spectrometry (TXRF) for Trace Selenium Determination in Soils", E. Margui et al., Anal. Chem., 82, 7744 (2010).

Electrons accelerated by the interaction between an ultrashort laser pulse and a plasma and then injected into a cold target can create X-ray photons via bremsstrahlung as well as inner shell ionization. The burst of K X-ray fluorescence from a metallic target is typically up to 10¹² photons/pulse with a duration of 100∼600 fs. Dr. F. Zamponi (Friedrich-Schiller-University Jena, Germany) and his colleagues have recently published an interesting report. Thin titanium foils were irradiated by ultraintense laser pulses at intensities up to ≈5×10¹⁹ W/cm², and X-rays emitted from the front and rear sides were measured using a high-resolution imaging system, which allows spectral analysis. During the experiments, they found significant differences in intensity, dimension, and spectrum between front and rear side X-ray emission in the 3~12 keV range. They explained such differences in terms of directional bremsstrahlung emission from fast electrons generated during the interaction process. For more information, see the paper, "Directional Bremsstrahlung from a Ti Laser-Produced X-Ray Source at Relativistic Intensities in the 3-12 keV Range", F. Zampon et al., Phys. Rev. Lett., 105, 085001 (2010).

The following awards were presented during the plenary session of the 59th Annual Denver X-Ray Conference: The 2010 Birks Award was presented to Victor Buhrke, Consultant, Portola Valley, CA to honor his significant contributions to the field of X-ray spectrometry. The 2010 Hanawalt Award was given to Takeshi Egami, University of Tennessee, Knoxville, TN and Simon Billinge, Columbia University, New York, NY. This award is presented every three years for an important, recent contribution to the field of powder diffraction.