The Raman intensities of the vibrational modes of doped (K+, Na+) NH4NO3 during phase transitions are shown behaving as power functions of |T-Tc|β. The exponent, β, is mode and degree-of-doping dependent. Among the modes, the totally symmetric ν1 mode of the nitrate ion possesses the unique behaviour of being a function of the degree of doping. The n1 mode also possesses the ability to differentiate between the different dopings with K+ and Na1. It is shown that the exponents are very sensitive to the degree of doping for very dilute doping where the so-called cross-over phenomenon between the n1 and other modes is observed. The physical interpretation is given in terms of the average distance between the doped ions.