Knowledge Bank

A beam maser spectrometer was used to make high resolution measurements (6 kHz f.w.h.m.) of $J=1\to 0$ transitions in $CH3\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CN$. Spectra of $CH3\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}CN$. were obtained at higher resolution using Ramsey’s method of separated oscillating fields. Analysis of the spectra yielded values for quadrupole coupling, spin-rotation and spin-spin interaction strengths. The $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ spin-rotation interaction strength was used to determine the paramagnetic contribution to the shielding tensor component $\sigma 1$. The diamagnetic contribution is obtained from molecular orbital calculations. Our results are compared with values obtained from liquid crystal and multiple pulse N.M.R. experiments.