The density matrix of a spinI= 5/2 excited by a radiofrequency pulse is calculated. The interaction involved during the excitation of the spin system is first order quadrupolar. Consequently, the results are valid for any ratio of the quadrupolar coupling, θQto the pulse amplitude θRF. The behaviour of the central and the two satellite line intensities versus the pulse length is discussed. The aluminium nuclei (27Al) in a single crystal of corundum (Al2O3) are used to illustrate some results.