Fragmentation of formic acid following photoexcitation around the carbon K edge

The fragmentation dynamics of core-excited methanoic acid (formic acid) has been studied by means of partial anion-and cation-yield measurements around the C K ionization threshold. All detectable ionic fragments are reported, and significant differences among partial-ion yields are observed. Possible dissociation pathways are discussed. We confirm experimentally the mixed A* molecular/3s Rydberg character of the resonance at 292.1 eV. Atomic rearrangements after photoabsorption leading to the formation of novel cationic fragments and selective fragmentation to the CH2O2+ ion are also reported.