Knowledge Bank

K Natural Cr (I = 0) and $\mathrm{<mrow\; data-mjx-texclass="ORD">53</mrow>}$Cr (I=3/2) (enriched to 96.9%) metals were vaporized and trapped in neon and argon matrices at $4\circ K$ . X-band ESR spectra contained at least 15 line structure lines belonging to two molecules, besides those due to Cr atoms. Hyperfine splitting patterns showed that $Cr2$ was not observed, supporting the assignment of its ground state as $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma$. Tentative analysis of the spectra indicates that both molecules are of high spin with the unpaired electrons is each interacting almost entirely with one Cr nucleus. Eight lines can be definitely assigned to one axial molecule (perhaps $Cr4$ with $C3v$ symmetry) and can be fit to within 3G with the following parameters: $S=3,g\perp =1.9970(2),g\Pi =1.9996(5),|D|=0.1101(3)cm-1,|\wedge \perp (unique53Cr)]=71.6(14)$ MHz. The remaining lines appear to belong to an axial molecule with S=4 or 5, which could be a slightly bent $Cr3$ with $C2v$ symmetry, in essential agreement with the Raman work of Dilella, et $al.1$ only the spectrum of this molecule appears in argon matrices.