Knowledge Bank

We are continuing the study of the infrared spectrum of the dimethylacetylene molecule for which we gave an initial report at last year's meeting. This talk will concentrate on the analysis of the perpendicular methyl rocking fundamental band in the region $1000-1100cm-1$ and the perpendicular methyl deformation fundamental band in the region $1350-1600cm-1$. The spectra were recorded at a temperature of -60C with a pressure of 1.4 Torr, an absorption path of 8 m, and a resolution of $0.0014cm-1$, using our modified double-pass Bomem FT spectrometer and cooled multiple-travarsal cell. We have made considerable progress with the analysis of the rocking fundamental band from which we obtain detailed information about the torsional barrier in the ground state and in the rocking fundamental state, as well as its variation with rotational state. We have also determined the extent and nature of the end-to-end coupling of the methyl rocking vibrations through the acetylenic bond.