Figure 2. Identification of ST’s in Ne matrix at 3K. Lower trace: 16O/18O decoupling effect for the resonant (ν2 + ν3)PDMST(ν2PA + ν3PD) transitions. 18O/16O isotopic ratios of (a) 0, (b) 0.2, (c) 5. The isotopic varieties of PA and PD are reported in this order. Upper trace: ST(ν1PA + ν1PD) observed at 7251.5 cm-1 in absence of resonance. R(0), P(1), Q(1): rovibrational transitions of H2O monomer.