Heisenberg spin exchange effects in powder spectra of weakly perturbed triplet states

Abstract

Heisenberg spin exchange effects on the powder spectra of weakly perturbed triplet states have been studied by simulation techniques. From very small exchange frequencies on, the derivative powder spectrum is dominated by a sharp, essentially constant width, central line whose amplitude exhibits very close to a square-root dependence on the exchange frequency. The derivative powder edge lines are shown to behave according to the single crystal limiting exchange width equation and it is shown that the frequency dependence of the central dominating line provides yet another measure of exchange parameters in physical systems. Application of these methods to the (φ3AsCH+3) (TCNQ)−2 ion radical salt yields results in good agreement with those obtained by other methods.