While the ST intensity was visible for >15 MHz (Figure ), the In CT linewidth was only ca. 400 kHz (Figure , Supplementary Figure ). At high frequencies, a quadrupolar CT lineshape from the 121 Sb site was clearly distinguished (Figure , Figure , Supplementary Figure ). The CT pattern of 121 Sb is an order-of-magnitude broader than the CT of In due not only to the higher C Q of the former in this sample but also the lower spin quantum number of 121 Sb (I = 5/2, see equation 1). The minor signal expected from In at low frequency was not readily observed (Figure , Supplementary Figure ).