We have applied Cavity Ring-Down Spectroscopy (CRDS) to investigate Nanosecond Repetitively Pulsed Discharge (NRPD) in nitrogen and air at atmospheric pressure in a pin-to-pin electrode configuration. We have measured the concentration of N₂(A) by probing absorption transitions in the near Infrared at 770 nm. We report on preliminary results about the measurement of the N₂(A) concentration and its evolution under different discharge regimes. We present here a comparison for an air plasma between the time evolution of N₂(A) measured by CRDS and the temporal evolution of atomic oxygen measured by two-photon absorption laser-induced fluorescence (TALIF). This study will allow us to compare our experimental results to those given by a kinetic model and help provide a better understanding of the plasma physicochemical processes.