Electron-impact cross sections for dipole- and spin-allowed excitations of hydrogen, helium, and lithium

Electron-impact excitation cross sections are presented for the dipole- and spin allowed transitions from the ground states to the np P-2 states for hydrogen and lithium, and to the 1snp P-1 states for helium, n = 2 through 10. Two scaling formulas developed earlier by Kim [Phys. Rev. A 64, 032713 (2001)] for plane-wave Born cross sections are used. The scaled Born cross sections are in excellent agreement with available theoretical and experimental data.