AbstractThe kinetic method has been applied in the determination of electron affinities (EA) of polycyclic aromatic hydrocarbons (PAHs) using electron attachment desorption chemical ionization mass spectrometry (DCI‐MS) and triple quadrupole tandem mass spectrometry. Electron‐bound dimers of PAHs (viz. solvated radical anions) are generated in the ion source and they fragment competitively upon collisional activation to yield the intact monomeric molecular radical anions. The ratio of the abundances of these two ions reflects the difference in electron affinities of the PAHs. Relative electron affinities are ordered as phenanthrene < perylene < 1,2‐benzanthracene < benzo [ghi] perylene < anthracene < pyrene < fluoranthene < biphenylene on the basis of multiple pairwise measurements. On the assumption that the effective temperature of the electron‐bound dimers is constant, under fixed desorption conditions, and using phenanthrene (EA = 0.307 eV), anthracene (EA = 0.556 eV), pyrene (EA = 0.591 eV) and fluoranthene (EA = 0.63 eV) as reference compounds, the electron affinities of several PAHs are estimated as perylene (0.35 eV), 1,2‐benzanthracene (0.39 eV), benzo [ghi] perylene (0.42 eV) and biphenylene (0.89 eV). The calculated effective temperature using the known EAs of the reference compounds, phenanthrene, anthracene, pyrene and fluoranthene, is 1251 K. The high effective temperature in the electron‐bound dimer is ascribed to both the weak binding in the electron‐bound dimer and to the choice of ionization conditions. The same methodology was applied to estimate the electron affinities of substituted PAHs. For alkyl‐substituted PAHs, e.g. 1‐methylanthracene, the estimated electron affinity (0.55 ± 0.10 eV) is consistent with electron transfer equilibrium studies. However, for halogenated PAHs, the ratio of fragment ion abundances does not correlate with the known electron affinity difference when a PAH and a halogenated PAH comprise the electron‐bound dimer. This is suggested to be due to differences in the structures of the cluster ions generated upon halogen substitution. The expected affinity results are obtained when the electron‐bound dimer is comprised of two halogenated PAHs. Estimated electron affinity values for 1‐bromopyrene (0.72 ± 0.10 eV) and 9‐bromoanthracene (0.61 ± 0.10 eV) are slightly higher than the electron affinities of pyrene and anthracene, respectively.