Coincidence Measurements on Ions and Electrons

Relative Partial Cross Sections for Single, Double, and Triple Photoionization of C60 and C70

“…A similar trend could be seen for C 70 and the corresponding ratio σ(70,2+)/σ(70,+) was 3−4, though there exists some scatter of the data points. These ratios for C 60 and C 70 are 1 to 2 orders of magnitude higher than those documented by many references dealing with photoionization of ordinary molecules. , Furthermore, the yields of fragment ions C 60-2 n + and C 70-2 n + ( n ≥ 1) are markedly lower than those of the parent ions. , The above observations are well-interpreted as that the excess internal energy is transmitted so quickly among enormous vibrational degrees of freedom that unimolecular reactions, such as direct dissociation, electronic predissociation, or coulomb explosion, are substantially suppressed and the lifetime of the parent ions is extended beyond the order of a millisecond. In other words, the overall rate of the internal conversion followed by intramolecular vibrational redistribution (IVR) may overwhelm that of dissociation into two or more singly charged fragments.…”

Differential cross sections for photo-double-ionization of the helium atom

“…Secondly, other sources of non-desired electrons, in particular electron scattering processes in the source region, turn out to be more important here. As a result one obtains an increase of non-coincident electrons in both spectrometers and, depending on the finite resolving time of the coincidence counting device, an increase in false coincidences which can approach an order of magnitude equal to that of the true ones (for the optimization of coincidence experiments see Eland and Schmidt (1996)). Generally one can say that finite resolving times can be treated sufficiently well in studies of PDI.…”

C 1s photoelectron angular distributions from fixed-in-space CO molecules in the high-energy continuum ≥50 eV

“…The doubly charged molecular ion of CO 2+ produced via the Auger decay immediately breaks up into two fragments, C + and O + for instance, by a Coulomb explosion. Then, 'coincidence measurements' [40] of the two fragments enable the determination of the molecular orientation at the instance of the photoemission. A previous study has reported that certain fragmentation channels that have smaller values of the kinetic energy release lead to the loss of information on the molecular axis [23].…”