Solomon echoes for spin 7/2 by soft pulse excitation

Solomon echoes are calculated for spin 7/2 in solids taking into account the first-order quadrupolar interaction while the pulses are on. The computation is performed using the algebraic computer program 'MAPLE'. Fifteen echoes are predicted and the amplitude of each echo is calculated. Each satellite transition produces five echoes whereas no echo is detected for the central transition. Among these echoes, six are 'forbidden' which are a result of the refocusing of exclusively multiple quantum coherences which are developed during the first pulse. These echoes cannot be predicted by a calculation based upon 'hard' pulse excitation. The results are valid for any ratio of the quadrupolar coupling to the frequency of the RF field (omega(Q)/omega(1)).