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Caption : 2d-pes matrix of the <i>m/z</i> 56 mass signals. 

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Caption : mass selected pepico spectra obtained at 15.5 ev for <i>m/z</i> 54 (red), <i>m/z</i> 27 (black) and <i>m/z</i> 26 (blue). the appearance energies are derived as the first point where the signal increases above the background. this method is less accurate than using recorded spes and hence we give an estimated error of 0.1 ev for the derived appearance energies.

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Caption : the spes corresponding to the mke trimer (<i>m/z</i> 168).

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Caption : peak evolution of the <i>m/z</i> 56 signal with increasing photon energy. 

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Caption : total ion yield (tiy) of the <i>m/z</i> 56 signal (black). by employing the same filtering as was done on the <i>m/z</i> 56 spes the signal can be disentangled into the contribution of the ionized mke monomer (red) and that of the c<sub>3</sub>h<sub>3</sub>o<sup>+</sup> fragments formed by dissociative ionization of the mke dimer.