Abstract: Evidence for intramolecular hydrogen exchange between OH and OCH, groups is observed in PIMS studies of deuterated analogues of the title compounds. Isotopic labeling demonstrates the unimolecular tautomerization of the molecular ion a, CH30CH2 (CH2), CH20H+., to structure b, CH20CH2 (CH2), CH20H2+. In the case m= 0, Lyman a photons (122 nm) from a hydrogen resonance lamp have an energy that corresponds to the first ...