Photoion—photoelectron coincidence PIPECO

In photoion—photoelectron coincidence (PIPECO), an ion M+ formed by PI is detected in delayed coincidence with the electron emitted [264, 266, 323, 324], If the energy of the emitted electron is measured and the photon energy is known, the internal energy of the ion M+ is known. Thus the reactions of ions with selected internal energies, E, can be studied by this technique. The statement that ions with selected internal energy states are studied , which appears often in the literature, seems too strong in the context of polyatomic ions. The total energy is selected, but further information about the states would have to be obtained by other means. 

Mass resolution in PIPECO measurements is typically very low and 13C isotope peaks, for example, cannot always be resolved. 

Charge exchange and collisional activation of energy-selected ions have been studied by PIPECO [21, 783]. 

The decompositions for which the energy release can be obtained with PIPECO occur in the ion source (i.e. before the reactant enters the acceleration region). The reaction time is, therefore, ill-defined [ A t (= t2 — t j) being of the order of microseconds]. 

---

In a further refinement of the photoionization method the kinetic energy of the photoelectrons produced is measured in coincidence with the photoion current this is the so-called photoion photoelectron coincidence (PIPECO) method. By this method, reactions of state selected ions can be direcdy monitored. This technique has been successfully applied to study... 

Metastable ions by photoion—photoelectron coincidence (PIPECO)... 

The translational energy releases reported in the literature for metastable ion decompositions are contained in Tables 1—7. Decompositions of positive ions occurring within an ion source are covered in Table 8 and decompositions of negative ions in an ion source in Table 9. Translational energy releases determined by photoion—photoelectron coincidence (PIPECO) appear, therefore, in Table 8. The results from the extensive series of electron impact (El) measurements [310] at ionizing energies close to threshold appear in Tables 8 and 9. Coverage of dissociations of diatomic ions is not exhaustive. 

---