Total, partial, and electron-capture cross sections for ionization of water vapor by 20-150 keV proteins

We present experimental results for proton ionization of water molecules ba sed on a novel event by event analysis of the different ions produced (and lost). We are able to obtain mass analyzed product ion signals (e,g., H2O+, OH+, O+, O++, H+) in coincidence with the projectile analyzed after the co llision, i.e., either being H+, neutral H after single electron capture dur ing the ionization event, or H- after double electron capture, after proper calibration we are thus able to determine a complete set of cross sections for the ionization of a molecular target by protons including the total an d the partial cross sections and in addition also the direct ionization and the electron capture cross sections.