Excitation of CO$^2$ by electron impact

The BE$f$ scaling\footnote{Y.-K. Kim, Phys. Rev. A {\bf 64}, 032713 (2001).} ---which converts plane-wave Born (PWB) cross sections for electron-impact excitations of atoms to accurate results at low incident electron energy $T$---is also found to provide results in excellent agreement with the new energy-loss experimental data for the A~$^1\Pi(v^{\prime}=n) \leftarrow$ X~$^1\Sigma(v^{\prime\prime}=0),\ n=$ 0--7 excitations of the CO molecule at $T=100$ eV. The new experimental data were measured at the Sophia Univ. using the same apparatus desribed in Green et al.\footnote{M. A. Green et al., J. Phys. B {\bf 35}, 567 (2002)} The unscaled PWB cross sections for the individual vibrational excitations were obtained by integrating the generalized oscillator strengths published by Chandranupong et al.\footnote{L. Chantranupong et al., Chem. Phys. {\bf 164}, 183 (1992).} The dipole $f$ values and excitation energies compiled by Berkowitz \footnote{J. Berkowitz, {\it Atomic and Molecular Photoabsorption}, Academic Press (2002)} are used to apply the BE$f$ scaling to the integrated (as opposed to angular distributions) PWB cross sections. Experiment at lower $T$ is in progress at Sophia Univ. to provide additional test of the BE$f$ scaling for molecules.