Browsing Research Articles (Physics) by Title

Now showing items 1-8 of 8

    • Femtosecond pump probe spectroscopy for the study of energy transfer of light-harvesting complexes from extractions of spinach leaves 

      Ombinda-Lemboumba, S.; Du Plessis, A.; Sparrow, R. W.; Molukanele, P.; Botha, L. R.; Rohwer, E. G.; Steenkamp, C. M.; Van Rensburg, L. (Academy of Science of South Africa (ASSAf), 2009-10)
      Measurements of ultrafast transient processes, of temporal durations in the picosecond and femtosecond regime, are made possible by femtosecond pump probe transient absorption spectroscopy. Such an ultrafast pump probe ...

    • Higher-order interference and single-system postulates characterizing quantum theory 

      Barnum, Howard; Muller, Markus P.; Ududec, Cozmin (Institute of Physics, 2014-12-10)
      We present a new characterization of quantum theory in terms of simple physical principles that is different from previous ones in two important respects: first, it only refers to properties of single systems without any ...

    • Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp 

      Baricholo, Peter; Hlatywayo, Dumisani J.; Von Bergmann, Hubertus M.; Stehmann, Timo; Rohwer, Erick; Collier, Mike (ASSAF -- Academy of Science of South Africa, 2011-11)
      A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury ...

    • International astronomer Phil Charles meets the ire of the National Research Foundation 

      Bohm, Lothar (Academy of Science of South Africa (ASSAf), 2010-03)
      Recent weeks have seen an embarrassing display of heavy-handed National Research Foundation (NRF) management in connection with the Square Kilometer Array (SKA) project – a new $2 billion radio astronomy facility to be ...

    • Internet access constrains science development and training at South African universities 

      Slippers, Bernard; Majozi, Thokozani; Nelwamondo, Fulufhelo V.; Steenkamp, Christine M.; Van Heerden, Esta; Wright, Caradee Y. (Academy of Science of South Africa (ASSAf), 2011-09)
      As a group of young scientists whose future careers depend increasingly on access to Internet resources, we are extremely concerned by the apparent lack of understanding of the stranglehold that current approaches to ...

    • Nonperturbative flow equations from running expectation values 

      Scholtz, F. G.; Bartlett, Bruce H.; Geyer, H. B. (American Physical Society (APS), 2003-08)
      We show that Wegner’s flow equations, as recently discussed in the Lipkin model, can be solved selfconsistently. This leads to a nonlinear differential equation which fully determines the order parameter as a function ...

    • Ultrafast dynamics of excitons in tetracene single crystals 

      Birech, Zephania; Schwoerer, Markus; Schmeiler, Teresa; Pflaum, Jens; Schwoerer, Heinrich (AIP Publishing LLC, 2014-03-18)
      Ultrafast exciton dynamics in free standing 200 nm thin tetracene single crystals were studied at room temperature by femtosecond transient absorption spectroscopy in the visible spectral range. The complex spectrally ...

    • White light wavefront control with a spatial light modulator 

      Dirk-Mathys, Spangenberg; Dudley, Angela; Neethling, Pieter H.; Rohwer, Erich G.; Forbes, Andrew (Optical Society of America, 2014-05)
      Spatial light modulators are ubiquitous tools for wavefront control and laser beam shaping but have traditionally been used with monochromatic sources due to the inherent wavelength dependence of the calibration process ...