Knowledge Bank

A search for electronic spectra of carbon chain molecules has been carried out in absorption at wavelengths down to 1100 A. The products from the evaporation of graphite from a tantalum cell were trapped in Ar at 8 K. A new band system with origin at 1875. A was observed to grow in simultaneously with the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\pi u-X1\Sigma g+$ transition of $C3$ which has been reported at 4102 A in Ar $matrices1$. It is argued that the new spectrum can be assigned to a transition from the ground state to the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma u+$ excited state of $C3$. Vibrational analysis yields the following frequencies: $\upsilon 1=1050cm-1,2\upsilon 2=570cm-1$, and $2\upsilon 3=1490cm-1$ which support the proposed assignment.