Differential cross sections at $0°$ and $180°$ for electron-impact excitation of the $E$ ${}^3{\Sigma }_g^{+}$ state of ${\mathrm{N}}_2$

Relative differential cross sections at forward and backward angles for excitation of the E ${}^3{\Sigma }_g^{+}$ state of ${\mathrm{N}}_2$ have been measured in the resonant, near threshold energy region. Measurements are performed by using a double trochoidal electron spectrometer and are calibrated on the absolute scale by simultaneous measurements of this process and vibrational excitation of the ground state of ${\mathrm{N}}_2$ via ${}^2{\Pi }_g$ resonance. The contributions at $0°$ and $180°$ are separated by electron beam modulation and time-of-flight detection of scattered electrons. Obtained results confirm directly theoretical predictions of the symmetry of angular distribution of scattered electrons from ${}^2{\Sigma }_u^{+}$ resonance.