Browsing by Author "Steenkamp, Christine M."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Accurate Laboratory Wavelengths of the A1Π(υ' = 0-5)-X1Σ+(υ'' = 0) Vibronic Bands of 12C17O and 12C18O
    (IOP Science, 2006) Du Plessis, Anton; Rohwer, Erich G.; Steenkamp, Christine M.
    Twenty nine rovibronic lines of 12C17O for which laboratory wavelengths were previously unavailable were detected in laser-induced fluorescence excitation spectra of the six vibronic bands A1Π(υ' = 0-5)-X1Σ+(υ'' = 0). Rovibronic lines of 12C16O, 13 C16O, 12C17O, and 12C 18O were detected in each band, allowing accurate determination of the unknown wavelengths using neighboring 12C16O and 13C16O lines as reference. The new wavelength data yield consistent heliocentric velocity values when applied to vacuum ultraviolet observations of 12C17O and 12C 18O in the interstellar medium.
  • Thumbnail Image
    Item
    Internet access constrains science development and training at South African universities
    (Academy of Science of South Africa (ASSAf), 2011-09) Slippers, Bernard; Majozi, Thokozani; Nelwamondo, Fulufhelo V.; Steenkamp, Christine M.; Van Heerden, Esta; Wright, Caradee Y.
    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 Internet pricing are placing on the development of science in South Africa.
  • Thumbnail Image
    Item
    Investigation of four carbon monoxide isotopomers in natural abundance by laser-induced fluorescence in a supersonic jet
    (Elsevier, 2007) Du Plessis, Anton; Rohwer, Erich G.; Steenkamp, Christine M.
    The four carbon monoxide (CO) isotopomers 12C16O, 13C16O, 12C18O and 12C17O have been detected simultaneously in a CO gas sample of natural isotopic abundance by measuring rovibronic excitation spectra of six vibronic bands in the Fourth Positive System. The CO sample was flow cooled by adiabatic expansion in a pulsed supersonic jet. The rovibronic excitation spectra were obtained using a novel pulsed laser source (pulse duration ∼25 ns, spectral bandwidth ∼5 GHz) continuously tunable in the 139–155 nm vacuum ultraviolet wavelength region for excitation and recording the total fluorescence. In the present paper we report on the spectroscopic results obtained, including transition wavelengths of three forbidden rovibronic bands (e3Σ− − X1Σ+(1, 0), d3Δ − X1Σ+(5, 0), a′3Σ+ − X1Σ+(14, 0)) of 12C16O and band origins of six rovibronic bands (A1Π(v′ = 0–5) − X1Σ+(v″ = 0)) of the rare isotopomer 12C17O, and on the experimental conditions facilitating the high sensitivity of the measurements. The exceptional sensitivity demonstrated by the results has been achieved by fine tuning experimental conditions including the conditions in the supersonic expansion, the jet pulse duration and the laser pulse timing.