Gd. Chen et al., ELECTRON-AFFINITIES AND C-60 ANION CLUSTERS OF CERTAIN BOWL-SHAPED POLYCYCLIC AROMATIC-HYDROCARBONS, Journal of mass spectrometry., 32(12), 1997, pp. 1305-1309
The kinetic method is applied to the determination of the electron aff
inities (EAs) of the bowl-shaped polycyclic aromatic hydrocarbons (PAH
s) dibenzo [a,g]corannulene (C28H14) 1 and dinndenochrysene (C26H12) 2
using electron attachment desorption chemical ionization mass spectro
metry (DCI-MS) and triple-quadrupole tandem mass spectrometry. The est
imated 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 comp
rising C-60 with 1 and C-60 with 2 were generated in the gas phase by
electron attachment desorption chemical ionization. The collision-indu
ced dissociation of each of these cluster ions yields both the monomer
ic radical anions as products and yields calculated electron affinitie
s of C-60 of 1.20+/-0.20 eV (C-60/1 dimer) and 1.24+/-0.20 eV (C-60/2
dimer). These values are significantly different from the known electr
on affinity of C-60 (2.65 eV) and support previous studies on electron
-bound dimers comprising C-60 and coronene [G., Chen, R. G. Cooks, E.
Corpuz and L. T. Scott, J. Am. Sec. Mass Spectrom. 7, 619 (1996)] in s
howing that the dissociation of electron-bound dimers comprising C-60
and reference PAHs is controlled by the electron affinity of a portion
of the C-60 surface, i.e. that a 'local' electron affinity of C-60 is
measured. The 'local' electron affinity value corresponds approximate
ly to the electron affinity of the reference PAHs, C-60 exhibiting an
affinity for the 'extra' electron in the cluster which approximately m
atches that of its PAH partner. (C) 1997 by John Wiley & Sons, Ltd.