Preferred fragmentation pathway for benzylpyridinium ions.
(a) Schematic view of the experimental setup showing the relative positions of the sample, time of flight start and stop detectors, 90% transmission grids, magnetic field, projectile (gold) flight path, proton (H+, blue) flight path, and secondary ion (green) flight path. Also shown are the accelerating electric fields within the ion extraction and ion detection regions along the secondary ion (green) flight path whenever (b) 5 kV or (c) 10 kV is applied to the sample and −2.2 kV is applied to the front of the ToF stop detector. Diagrams not drawn to scale.
Mass spectrum of p-CH3 BPY generated by 440 keV Au400 +4 impacts using a 10 kV secondary ion accelerating voltage. Fragmentation tail is highlighted in red and the area integrated for the fragment peak is shaded.
Survival yield values for five BPY ions generated by 440 keV Au400 +4 impacts. Survival yields were measured using a 10 kV ion extraction voltage and are plotted using the CCSD(T)/BSII//B3LYP/BSI dissociation energies. The data are fitted with a sigmoidal breakdown curve which displays the asymptotic behavior of the predicted survival yield for theoretical molecules with much lower or much higher bond dissociation energies.
Dissociation energies calculated for five different benzylpyridinium ions at various levels of theory.
(a) Rate constant and (b) lifetime distributions measured for four BPY ions generated by 440 keV Au400 +4 impacts.
Plots for four BPY ions showing the sum of states calculated at each step along their fragmentation pathways at an internal energy of 5.95 eV.
RRKM relations calculated for four BPY ions.
(a) Total internal energy distributions measured for the p-OCH3, p-CH3, p-Cl, and p-CN BPY ions. Distributions are also normalized (b) to the number of atoms and (c) to the number of degrees of freedom.
CCSD(T)/BSII//B3LYP/BSI dissociation energies for the full series of BPY thermometer ions.
Summary of experimentally measured parameters for selected BPY thermometer ions.
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