10min:

M. ISABEL PENA, VANESA VAQUERO, JUAN C. LÓPEZ AND JOSÉ L. ALONSO, Grupo de Espectroscopía Molecular (GEM), Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain.

The rotational spectra of the nitrogen bases uracil (m.p. 335~^\circC) and thymine (m.p. 316~^\circC) have been observed in the 6-18 GHz frequency range by using a Laser-Ablation Molecular Beam Fourier Transform Microwave Spectrometer (LA-MB-FTMW).\footnote ~A.~Lesarri, S.~Mata, J.~C.~López and J.~L.~Alonso, Rev. Sci. Instrum. , \textbf74, 4799 (2003). The nuclear quadrupole coupling hyperfine structure corresponding to the presence of two ¹⁴N atoms has been completely resolved for both molecular systems. The rotational spectrum of all uracil ¹³C and ¹⁵N monosubstituted isotopomers in their natural abundance are being observed. Following the characterization of these isotopomers, the uracil structure in gas phase will be obtained.