Interaction of slow electrons with methyl phosphate esters

We report computed cross sections for low-energy elastic collisions of electrons with the methyl esters of phosphoric acid, monomethyl, dimethyl, and trimethyl phosphate, and with phosphoric acid itself. For phosporic acid and monomethyl phosphate, polarization effects are included in the calculation, while the two larger molecules are treated in the static-exchange approximation, that is, with polarization neglected. The integral elastic cross sections exhibit broad shape resonances above 5 eV that give rise to strong variations in the differential cross section with energy. However, no shape resonances are evident below 5 eV. We compare our results to previous calculations and measurements and discuss their relevance to electron-induced damage to the DNA backbone.