Knowledge Bank

The rotational spectra of deuterated acetylene dimers, which were produced in a molecular beam at 1 K using 1% mixtures of HCCH, DCCH, and DCCD in Ar, were observed with a pulsed beam Fourier transform microwave spectrometer. All types of the deuterated acetylene dimers in which a D atom participates in the hydrogen-bond were observed, i.e. $(DCCD)2,(DCCH)2$, DCCD-DCCH, DCCH-DCCD, HCCH-DCCD, and HCCH-DCCH. However, we could not detect any form of the mixed H/D dimers in which the hydrogen atom is located in the hydrogen-bond. From the interconversion tunneling spectra, the tunneling potential of (DCCD)$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ was analyzed by using a one-coordinate model (Fraser et $al.1$) and the potential depth was determined to be $V4=35.577$ $cm-1$, which is $2.371cm-1$ deeper than that of $(HCCH)2$ studied by Fraser et $al.1$ Also we applied a modified version of the one-coordinate model was also applied to the other deuterated acetylene dimers. A discussion of the observed spectra and tunneling model will be presented.