Fig. 4

Near-field and far-field measurements. a Sketch of the photoemission electron microscopy (PEEM) configuration with two kinds of laser sources. b, c Far-field spectra (solid lines) and near-field photoemission (PE) intensity curves with different detuning characteristics. In b, the 400 nm period and 115 nm nanoblock correspond to the large detuning conditions (221 meV). In c, the 500 nm period and 115 nm nanoblock correspond to the small detuning conditions (25 meV)