Electron impact excitation of the electronic states ofN2. III. Transitions in the 12.5-14.2-eV energy-loss region at incident energies of 40 and 60 eV

Normalized absolute differential and integral cross sections for electron-impact excitation of five optically-allowed singlet states, two known triplet states, and two unknown triplet-like states of ${\mathrm{N}}_2$, lying in the energy-loss range 12.5-14.2 eV, have been determined by analysis of electron energy-loss data at incident electron energies of 40 and 60 eV. The range of scattering angles considered in this work was 5° to 138°. The optically allowed transitions are to the $b{}_{}{}^1{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$, $c{}_{}{}^1{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$, $c^{\prime }{{}_{}{}^1{}_{}{}^{}\Sigma _u^{}{}_{}{}^{}}^{+}$, $o{}_{}{}^1{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$, and $b^{\prime }{{}_{}{}^1{}_{}{}^{}\Sigma _u^{}{}_{}{}^{}}^{+}$, states and the known triplet excitations are to the $F{}_{}{}^3{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$ and $G{}_{}{}^3{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$ states. Cross sections for excitation to two unidentified triplet-like states at 13.155 and 13.395 eV were also obtained from the data analysis. The relationship of the generalized oscillator strength for the dipole-allowed states obtained from the present measurements to known optical oscillator strengths is discussed.