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WEI LIN, WALLACE C. PRINGLE, STEWART E. NOVICK, Department of Chemistry, Wesleyan University, Middletown, CT 06459; THOMAS A. BLAKE, Pacific Northwest National Laboratory, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC05-76RLO 1830); JOHN C. KESKE AND DAVID F. PLUSQUELLIC, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8441.
Tropolone is a seven-membered ring with an intramolecular hydrogen bond between the hydroxyl proton on C1 and the carbonyl oxygen on C2. The proton tunnels between the two neighboring oxygen atoms. Microwave spectra of singly-substituted 18O-tropolone and of singly-deuterated tropolone were measured to determine the effect of these two substitutions on the proton tunneling dynamics. The 0+ state of 18O-tropolone and both the 0+ and 0- states of D-tropolone were observed and assigned. Analysis of the spectra reveals complete quenching of the tunneling splitting of 18O-tropolone. The energy separation between the 0+ and 0- states in D-tropolone was determined and is found to be significantly smaller than that of normal tropolone.