  The non-equilibrium ro-vibrational distribution functions of molecules in a
plasma can heavily influence the discharge operation and the plasma-chemistry.
A convenient method for measuring the distribution function is by means of
coherent anti-Stokes Raman scattering (CARS). CARS spectra are measured in a
ns-pulsed plasma between two parallel, 1 mm spaced molybdenum electrodes in
nitrogen at 200 mbar with pulse durations of 200 ns / 250 ns and a repetition
rate of 1 kHz. The CARS spectra are analyzed by a fitting routine to extract
information about the vibrational excitation of the nitrogen molecules in the
plasma. It is found that during the discharge the vibrational distribution for
$v \lesssim 7$ can be described by a vibrational two-temperature distribution
function. Additionally, the electric field is measured by the E-FISH method
during the discharge pulse. It is found to be constant in time after the
initial ionization wave with values close to 81 Td for the investigated
conditions. During the afterglow between two discharge pulses a more general
fitting approach is used to obtain the population differences of two
neighboring vibrational states. This allows to capture the more complex
vibrational dynamics in that time period. The measurement results are discussed
in more detail and compared to simple models in a companion paper.
