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Cover Picture: Experimental Detection of the H2NO3 Radical (ChemPhysChem 10/2003)
The cover pictures shows...‥the mass spectrum of nitrogen hydroxide oxide, the H2NO3. radical, which was discovered by neutralization reionization mass spectrometry (NRMS) and characterized as a relatively long-lived (over 1 μs) metastable species. The discovery required the availability of the appropriate charged precursor that fortunately had previously been prepared by this group (1989) as a result of their sustained interest in gas-phase ion chemistry of nitrates, nitrites and related molecules. Cacace et al. found that protonation of nitric acid by strong Brønsted acids yields, in addition to the H2O-NO2+ ion, smaller amounts of the less stable (HO)2NO+ isomer, namely charged nitrogen hydroxide oxide. This result has allowed the present discovery by NRMS (yellow trace), whereas NRMS of the H2O-NO2+ ion does not result in detectable H2NO3. neutral species (green trace). The importance of nitrogen hydroxide oxide stems from its relevance to a variety of research areas, from the reduction of the NO32− anion, to atmospheric chemistry, radiolysis of nuclear-waste solutions, the charge-transfer mechanism of aromatic nitration, etc. Find out more in the communication by Cacace et al. on pp. 1128–131.