Rate of rotation of methyl groups

 Dear Colleagues:
      I am seeking information on the rate of rotation of methyl groups:
      (i) firstly, I am seeking information/references describing the rate of
 rotation of the terminal methyl groups of n-alkanes at ca. room temperature
 (either experimental or theoretical).
     (ii) secondly, I am seeking information/references describing the rate of
 rotation of the C-19 methyl groups of steroids (or the rate of rotation of
 methyl groups attached to structurally related, hindered quaternary carbon
 atoms) at ca. room temperature (either experimental or theoretical).
    (iii) finally, I am seeking information/references on the RELATIVE rates
 of rotation of perhydro and isotopically substituted methyl groups.  For
 example, what would one expect to be the rate of rotation of a chiral methyl
 group (CHDT) RELATIVE to a nonchiral perhydro methyl group (CH3) in the same
 molecule at the same temperature?
      I thank all responders for generously sharing their information/calcula-
 tions with me.
 Yours respectfully,
 (Dr.) S. Shapiro
 Institut fuer orale Mikrobiologie und allgemeine Immunologie
 Zentrum fuer Zahn-, Mund-, und Kieferheilkunde der Universitaet Zuerich
 Plattenstrasse 11
 Postfach
 CH-8028 Zuerich, Switzerland
 Internet: toukie &$at$& zui.unizh.ch
 FAX-nr: ( ... + 1) 261'56'83