Knowledge Bank

Pure carbon molecules have been trapped in neon and argon matrices at $4\circ K$ from the vapor over thermal- or laser-heated graphite or from the microwave discharge of traiacetylene in argon. Linear triplet $C4$ has previously been identified.1 Corresponding signals attributed to a linear $C6$ molecule in a $3\Sigma$ state, probably the ground state, are also observed. $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ nuclear hyperfine structure again supports a cumulene-type bonding. The zero-field-splitting parameter was found to be $|p|=0,363cm-1$ (in neon), about $50\circ$ larger than that of $C4$. These results will be discussed relative to recent ab initio $calculations.2,3$