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The study of the ionic solutions is of long history and of great interest to many research fields ranging from medicine to energy.An important,but not yet clearly addressed,issue in ionic solution research is whether cations and anions can associate to form ions pairs or clusters in the strong electrolyte solutions with a medium concentration.Most of the experimental evidences in favor of the existence of ion pairing are indirect and at the macroscopic level.The solution vibrational spectroscopies provide powerful means to reveal the ionic solution physics at the microscopic level,but their interpretation usually requires the help from theoretical spectroscopic modeling.The modeling of the vibrational spectroscopy of the ionic solutions is difficult due to the highly disorder nature and strong induced polarization of the system.We developed a theoretical protocol which can simulate these vibrational signals comparable with the experiment based on the trajectory ensemble generated using the molecular dynamics simulations.The protocol includes a dipole-induced-dipole scheme to treat the induced polarization and a unified stability matrix method to simulate different signals.Our simulations and analysis revealed that certain dynamical heterogeneities induced by ion pairing are detectable using the vibrational spectroscopic means including the ultrafast infrared,the dielectric relaxation and the optical kerr effect techniques.