CROSS SECTIONS FOR ELECTRON EXCITATION OF THE 3914-A (0,0) BAND OF THE N2(+) FIRST NEGATIVE SYSTEM

As part of a study of the emission from nitrogen excited by an electron beam, cross sections for electron excitation of the 3914-A (0,0) band of the N2(+) first negative system were measured for electron energies of 95 to 2023 eV. Because published values for these cross sections differ by factors of two to three, an effort was made to establish the accuracy of the measurements. 3914-A band intensity was measured with two independently calibrated photometers and a scanning spectrometer. A comparison of equipment and joint observations were made with experimenters from two other laboratories. The cross section obtained for the 3914-A band at 95 eV is 1.5 x 10 to the -17th power sq cm, and that at 2023 eV is 3.1 x 10 to the -16th power sq cm. By a simple calculation, one can derive a corresponding efficiency of 0.0043 for the production of the 3914-A band by electrons in air. The excitation cross sections are in reasonable agreement with other recent measurements, but are higher than some values reported earlier. The calculated efficiency is in fair agreement with the results of laboratory efficiency measurements.