BEAM-INDUCED REACTION BETWEEN METANITROBENZYL ALCOHOL AND DIPYRIDOCYANINE DYES IN LIQUID-SECONDARY-ION MASS-SPECTROMETRY

Analyses of cationic dipyridocyanine dyes by liquid-secondary-ion mass spectrometry in a liquid matrix of meta-nitrobenzyl alcohol (mNBA) pr ovide evidence for beam-induced addition reactions between the sample molecule (C) and the mNBA solvent. The ionic products of these additio n reactions formally correspond to [C + mNBA - O-2](+), [C + mNBA - O- 2 - H](+); and [C + mNBA - O-2 - 2H](+). Initial loss of H from the ad duct ion extends the conjugation of the adduct into the mNBA ring stru cture, whereas the final loss of hydrogen is thought to be promulgated by the formation of a benzylic radical stabilized through resonance w ith the pi-electron system of the nitrobenzyl alcohol. Alternatively, two hydrogens may be lost from the alcohol functionality to form an al dehyde.