Fragmentation of chlorpyrifos by thermal electron attachment: a likely relation to its metabolism and toxicity.The energies of formation and dissociative decays of temporary negative ions of the organophosphorus insecticide chlorpyrifos (CPF) are studied using electron transmission spectroscopy (ETS), dissociative electron attachment spectroscopy (DEAS) and quantum-chemical calculations.  Most of the negative fragments are detected by DEAS at thermal energies of the incident electrons, being thus associated with the dissociation of stable (vibrationally excited) negative ion states formed by electron attachment into the π* LUMO and LUMO+1. 
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