Dynamic frequency shifts in pseudorotating Na3

摘要

ESR spectra assigned to pseudorotating Na3molecules have been obtained by clustering atomic sodium in an argon matrix. Both a pseudorotating spectrum and the previously reported rsquo;rsquo;stationaryrsquo;rsquo; spectrum are observed. As in the analogous potassium case, the pseudorotating spectrum is attributed to a rapid exchange between the three equivalent potential wells of a Jahnndash;Teller distorted trimer. The ESR spectra show an extreme alternating linewidth effect. Even atTgsim;30 K, only those four hyperfine (hf) components which do not broaden are observed. The relaxation matrix formalism is applied to pseudorotating Na3and derived expressions give a good fit to the measured line positions. These show 5ndash;10G rsquo;rsquo;dynamic frequency shifts,rsquo;rsquo; much larger in magnitude than normally encountered in exchanging radicals. The measuredgvalue and hf constants for pseudorotating Na3are in close correspondence with those predicted from the stationary trimer parameters. Together the two spectra determine the sign of the hf coupling in Na3.