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Thin film-silicon bilayers have been used to generate surface plasmas in air at atmospheric pressure, using nanosecond pulsed discharges. At low pulse repetition frequency (PRF), the deposition of an alumina film of 40 nm thickness on a silicon substrate enables the surface propagation of a discharge otherwise localized near the anode. At high PRF, in situ Raman microspectroscopy has been employed to track changes to the surface due to the plasma in real time with a resolution of 1 s. Depending on the duration of plasma operation, the Raman spectrum of the optical phonon of silicon undergoes a shift to lower wavenumber and asymmetric broadening, or a pure enhancement in intensity. These changes are consistent with the presence of nanostructured silicon. Ex situ scanning electron microscopy confirms that such structuration occurs at several size scales, down to nanoparticles about 50 nm in diameter.