A type of ionic crystal structure in which the cations have an expanded face-centered cubic arrangement with the anions occupying both types of tetrahedral hole. The cations have a coordination number of 8 and the anions have a coordination number of 4. Examples of compounds with this structure are CaF2, BaCl2, and PbO2. The antifluorite
A benzodiazepine used medically in some countries as a powerful hypnotic, sedative, and muscle relaxant. It was marketed in the US under the trade name Rohypnol. Flunitrazepam has become notorious as a so-called ‘date rape’ drug. It is quickly eliminated from the body, difficult to detect, and causes amnesia, so that victims cannot remember events
A sequence of pulses used for spin-echo experiments in nuclear magnetic resonance (NMR) in which the initial pulse is 90° followed by a series of 180° pulses. A CPMG sequence is designed so that the spin echoes die away exponentially with time. Spin-spin relaxation occurs characterized by a time constant T2, which can be determined