The morning session comprised of the presentation of three short papers, namely: 'The 31P n.m.r. of Phosphorus Halide Derivatives' by Dr K. Dillon, University of Warwick.
'The Use of a Computer of Average Transients for Resolution Enhancement' by Dr A. J. Everett and Mr A. Ferridge, Wellcome Research Laboratories. 'Ionization of acids studied by n.m.r.' by Dr T. H. Lilley, University of Sheffieid. and a longer paper entitled: 'Intermolecular Effects in Proton Magnetic Resonance' by Dr W. T. Raynes, University of Sheffield.
The short paper presented by Dr Everett promoted more than the usual discussion on account of the possible wider applications of the method used for the resolution enhancement, the application of the method to everyday problems was clearly indicated by the very elegant examples, of the application of this technique, given in the paper.
The afternoon session was devoted to a general discussion on the problems of the presentation of n.m.r. data. The Hon. Secretary presented the results of the questionnaire which had been circulated to all Group Members, but pointed out that while the majority felt that low field shifts should be presented as negative values many found this inconvenient for proton shifts. I n consequence of this there was almost equal support for the tau and delta proton scales. Dr Sutcliffe, however, forcibly pointed out the advantages of considering the scale on the frequency scale and, as decreasing field corresponds to increasing frequency, low field shifts of necessity become positive.
The advantages of using the frequency for the consideration of the chemical shifts may be briefly summarised as follows:
(a) The frequency of a transition may be directly related to the energy by the well known equation. Frequency is thus a more fundamental basis on which to consider n.m.r. spectra than the field strength.
(b) The spectra are additionally calibrated on the frequency scale without reference to the precise field strength. The dimensionless ppm scale of chemical shifts is still retained and this is still expressed as a ratio of two frequencies, i.e. the separation of a signal on the frequency scale (Hz or c.s.?) divided by the resonance frequency of the nuclei being considered.
(c) This system will naturally be more useful when measuring frequency swept spectra, a technique which is becoming more widely used.