SECONDARY-ELECTRON ANALYSIS OF POLYMERIC IONS GENERATED BY AN ELECTROSPRAY ION-SOURCE

Electrospray mass spectra of biopolymeric ions can be used to determin e ion masses using secondary electron pulse spectra. Secondary electro n yields reflect electronic excitation deposited in a solid target, wh ich is related to the electron density and velocity of projectile ions . Secondary electron pulse spectra provide a fingerprint which measure s masses of ions of known velocity. Ions with masses from 411 (tetrahe ptylammonium ion) to 480 000 (apoferritin) amu give secondary electron yields that fall on a single curve of secondary electrons/amu plotted as a function of ion velocity. Secondary electron analysis revealed d ecomposition of larger polyethylene glycol ions (m > 10 000 amu).