ESR OF PSEUDOROTATING $^{6}Li_{3}$, AND $^{7}Li_{3}$

Abstract

ESR spectra assigned to pseudorotating $^{6}Li_{3}$, and $^{7}Li_{3}$, molecules have been produced by are lamp photolysis of argon matrices doped with isotopically enriched $^{6}Li$ or $^{7}Li$. The spectrum of $^{6}Li$, consists of 7 equally spaced first derivative transitions with relative intensities (1.1:3.3:6.2:7.0:5.7:3.0.1.1) in good agreement with the expected values for 3 equivalent 1 = 1 nuclei. The measured hf constant and g value are $$ 12.21(1) G and $g_{o}$ 2.00282(1). The absence of a ``stationary” trimer spectrum suggests that the ground vibronic state of $Li_{8}$ is non-localized as predicted by ab initio calculations. The total isotropic spin population of the triner $(\Sigma_{0} = 0.68)$ suggests that the unpaired electron wave function has an approximately 30% p-character. A comparison of the orbital composition of $M, M_{2}, M_{3}, M\infty (M = Li, Na, K)$ shows (1) a diminishing s-character with increasing cluster size, (11) a remarkable similarity between Na and K cluster far all sizes, and (iii) a markedly smaller s-character for Li clusters. $^{1}$W.H. Gerber and C. Schunacher, J. Chem. Phys. 69, 1697 (1978).