Extracting site-specific information about bond rearrangement during ethanol photofragmentation*

Ethanol (CH₃CH₂OH) has three locations for hydrogen atoms: the hydrogen that is part of the hydroxyl group, the three β-hydrogens attached to the carbon atom opposite the hydroxyl group, and the two α-hydrogens attached to the central carbon atom.  When studying bond rearrangement initiated by an ultrafast laser pulse, such as the production of H₃⁺ photofragments, it is desirable to be able to know which sites contribute hydrogen atoms to the final product.  Here we describe a technique that combines COLTRIMS data obtained using different isotopologues of ethanol under identical laser pulse conditions (800 nm central wavelength, 3.0×10¹⁴ W/cm² peak intensity, 23 fs FWHM) to extract site-specific data about the formation of H₃⁺ following double-ionization of the parent molecule.