BROADBAND CHIRPED-PULSE FOURIER-TRANSFORM MICROWAVE SPECTROSCOPIC INVESTIGATION OF THE STRUCTURES OF THREE DIETHYLSILANE CONFORMERS

Abstract

The rotational spectrum of diethylsilane has been assigned using broadband chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy. Previously, Fourier-transform microwave rotational spectra were observed using a Balle-Flygare type instrument for the $^{28}$Si isotopologues of the gauche-gauche, trans-gauche, and trans-trans conformers., (2009), DOI: 10.1021/jp811049n.} In the present study, a broadband microwave spectrum was obtained at the University of Virginia, taking advantage of the ability to perform deep signal averaging to increase the measurement sensitivity. To obtain a full structural determination of the conformers of this molecule, spectra for the $^{29}$Si, $^{30}$Si, and single $^{13}$C substitutions for the gauche-gauche, the trans-gauche, and the trans-trans species were assigned. Substitution ($r_s$) structures and inertial fit ($r_0$) structures were determined and a comparison between the experimental and ab initio structures will be presented. For the $^{28}$Si isotopologues, the percent differences between the experimental and ab initio rotational constants are less than 1.5\% for the trans-trans and trans-gauche and are between 2.0 and 5.0\% for the gauche-gauche conformer. The structural parameters will be compared between this molecule, diethylgermane and other silicon containing molecules and the relative abundances of the three conformers will be discussed.