Photoelectron photoion coincidence

A number of optical photoion-photoelectron coincidence experiments have been reported107 giving qualitative information on molecular breakdown. However, in these experiments little or no attempt has been made to correct for either the transmission efficiency of the photoelectron spectrometer or the ion kinetic-energy discrimination. Fragment ions usually... 

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... 

Figure 11. Photoion photoelectron coincidence studies of charge-transfer reactions of state-selected ions. Cross sections for nitric oxide symmetric charge-transfer reaction are plotted as function of reactant-ion kinetic energy and reactant-ion vibrational state (o = 0,1,2,3,4,5). Solid lines are linear least-squares fits to experimental data (not shown).86c...

Figure 29. Relative cross sections for collisional dissociation of CHjBr in selected vibrational-energy states as function of kinetic energy. Data were obtained by photoion photoelectron coincidence technique and were analyzed by assuming only backscattering in center of mass. Maxima of curves were normalized to same relative cross section.86b...

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. 

Breakdown diagrams can be constructed on the basis of charge exchange mass spectra [812, 813]. In the ideal case, these would be identical to those obtained by photoion—photoelectron coincidence, provided the sampling intervals, and t2 in eqn. (9), were the same in the two experiments. 

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. 

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