Absolute cross-sections for dissociative photoionization of some small esters

The first measurements of absolute cross-sections for near-threshold molecular and dissociative photoionization are presented for 11 small esters (methyl formate, ethyl formate, vinyl acetate, methyl propanoate, ethyl propanoate, methyl butanoate, methyl isobutanoate, methyl propenoate, ethyl propenoate, methyl crotonate, and methyl methacrylate). Photoionization mass spectrometry (PIMS) is employed with an energy resolution of 40 meV (fwhm) using a monochromated VUV synchrotron light source. An extensive literature exploring isomerization/dissociation mechanisms is available for six of these molecules. There are, however, no previous observations of dissociative ionization for four simple monounsaturated esters (methyl propenoate, ethyl propenoate, methyl crotonate, and methyl methacrylate), and dissociative ionization of ethyl propanoate has received scant attention. Appearance energies for dissociative photofragment ions of these five molecules are presented.

Graphical abstractThe first measurements of absolute cross-sections for near-threshold molecular and dissociative photoionization are presented for 11 small esters (methyl formate, ethyl formate, vinyl acetate, methyl propanoate, ethyl propanoate, methyl butanoate, methyl isobutanoate, methyl propenoate, ethyl propenoate, methyl crotonate, and methyl methacrylate).Figure optionsDownload full-size imageDownload high-quality image (96 K)Download as PowerPoint slide