Excitation of the six lowest electronic transitions in water by 9–20 eV electrons

We report differential and integral cross sections for excitation of the ^(3)B_1, ^(1)B_1, ^(3)A_2, ^(1)A_2, ^(3)A_1 and ^(1)A_1 states of H_(2)O by 9–20 eV electrons. The measurements are taken by conventional differential electron energy loss spectroscopy techniques, while the calculations employ the Schwinger multichannel method within a ten-channel approximation. The new data are compared with previous experimental and theoretical results. The present measurements and calculations agree reasonably well both with each other and with prior theoretical efforts but show discrepancies with prior measurements. Reasons for those discrepancies are considered and discussed.