Journal of Chemical Physics
We have measured proton Zeeman relaxation rates R in the 2,4- and 2,5-isomers of di tert-butylhydroxybenzene (DTHB) in the solid state. R was measured as a function of temperature T at proton Larmor frequencies of (j)/21T = 8.50,22.5, and 53.0 MHz. The Tranges were from 78 K to just below the melting points of 2,4- and 2,5-DTHB, 385 and 323 K, respectively. The 2,5- DTHB R vs T and (j) can be interpreted qualitatively in terms of three Bloembergen-PurcellPound (BPP) spectral densities, one for each of the three types of rotors in the molecule. The quantitative agreement is poor but a good fit is obtained using either a Davidson-Cole (DC) or Frolich spectral density, still preserving the three rotor types. The implications of this are discussed. The BPP and DC spectral densities fail completely in interpreting R vs T and (j) for 2,4- DTHBwhereas good quantitative fits are obtained using a Frolich spectral density. The distributions of activation energies characterizing the three rotor types are so wide for the Frolich spectral density fit of the 2,4-DTHB data that the individual rotor types lose their identity.
Copyright (1986) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Chem. Phys. 84, 1959 (1986) and may be found at http://jcp.aip.org/resource/1/jcpsa6/v84/i4/p1959_s1.
P.A. Beckmann et al, J. Chem. Phys. 84, 1959 (1986).