Journal Archive Collections

Permanent URI for this communityhttp://localhost:4000/handle/123456789/16937

Browse

Author: search.filters.author.Borgers, Adriaan JStart date: 1980

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Radiofrequency Resonance Study of Alkali Metal Ionization in a Carbon Monoxide Flame Part 2.—Determination of the Ionization Rate Constants for Caesium, Potassium, Sodium and Lithium
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (05), 1981) Borgers, Adriaan J; Jongerius, Michiel J; Ventevogel, Wim J
    The collisional alkali-ionization rate constants, ki, for an atmospheric-pressure CO/O2/N2 flame of well-known temperature (1930 K) and composition have been redetermined using the r.f. resonance method. The values of ki were obtained from the r.f. bandwidth measured as a function of risetime. Hydroxide formation was found to play a substantial role in the case of lithium only. Attention is given to the mathematical procedure which enabled the simultaneous determination of the sensitivity of the r.f. resonance system (whose design and performance were described in Part 1) as well as the value of ki; in the case of Li, where the association factor ϕ[LiOH]/[Li] appeared to depend upon height, a different procedure was necessary. Our experimental values of ki, which are found to be independent of alkali concentration, are: ki(Cs)= 0.47 × 102, ki(K)= 13.4, ki(Na)= 0.30 and ki(Li)= 0.13 s–1. These values are compared critically with the results from literature; within this context we discuss to what extent chemi-ionization, electron attachment, (ambipolar) diffusion and hydroxide formation may be responsible for systematic errors.
  • No Thumbnail Available
    Item
    Radiofrequency Resonance Study of Alkali Metal Ionization in a Carbon Monoxide Flame Part 1.—General Design of the Radiofrequency System
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (05), 1981) Borgers, Adriaan J; Jongerius, Michiel J; Hollander, Tjalling
    In Part 1 an analysis is given of the radiofrequency resonance technique. This technique is used for investigating alkali metal ionization relaxation in a carbon monoxide flame (see Part 2). The r.f. resonance measurements yield direct information about the densities of the electrical-charge carriers in the flame plasma. These densities are determined as a function of rise-time of the flame gases. In this context the advantages and disadvantages of the method in comparison with probe technique and microwave methods are discussed. However, we would emphasize that it is not necessary to restrict the application of the r.f. resonance method to the analysis of ionization phenomena in flames. Since we are interested in small differences in electron density we would note that our r.f. resonance method which operates on the h.f. band (3–30 MHz), is more sensitive in the detection of electrons than microwave methods. Under our experimental conditions the minimum detectable electron density (variation) was 0.6 × 108 cm–3. A linear response of the r.f. system exists only for electron densities < 1 × 1010 cm–3. The temporal resolution in our kinetic studies is ca. 1 ms, depending on condenser dimensions as well as flame rise velocity.