The kinetic method is applied to the determination of the electron affinities (EAs) of the bowl-shaped polycyclic aromatic hydrocarbons (PAHs) dibenzo [ a,g ] corannulene 1 and diindenochrysene 2 using elec-(C 28 H 14 ) ( C 26 H 12 ) tron attachment desorption chemical ionization mass spectrometry (DCI-MS) and triple-quadrupole tandem mass spectrometry. The estimated EAs of 1 and 2 are 1.00 » 0.20 and 1.16 » 0.20 eV respectively. In an analogous experiment, loosely bound dimeric radical anions comprising with 1 and with 2 were generated in the gas C 60 C 60 phase by electron attachment desorption chemical ionization. The collision-induced dissociation of each of these cluster ions yields both the monomeric radical anions as products and yields calculated electron affinities of of C 60 1.20 » 0.20 eV dimer) and 1.24 » 0.20 eV dimer). These values are signiÐcantly di †erent from the (C 60 /1 ( C 60 /2 known electron affinity of (2.65 eV) and support previous studies on electron-bound dimers comprising and C 60
C 6O coronene [ G. Chen, R. G. Cooks, E. Corpuz and L. T. Scott, J. Am. Soc. Mass Spectrom. 7, 619 (1996) ] in showing that the dissociation of electron-bound dimers comprising and reference PAHs is controlled by the C 60 electron affinity of a portion of the surface, i.e. that a "localÏ electron affinity of is measured. The "localÏ C 60 C 60 electron affinity value corresponds approximately to the electron affinity of the reference PAHs, exhibiting C 60 an affinity for the "extraÏ electron in the cluster which approximately matches that of its PAH partner.
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