New γ transitions have been identified in argon isotopes in 40 Ar + 208 Pb multiple transfer reactions by exploiting, in a fragment-γ measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large γ arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states.