Study of surface plasmon polariton (SPP) dynamics with interferometric time-resolved photoemission electron microscopy (ITR-PEEM) Part 2:
By using interferometric time-resolved photoemission electron microscopy (ITR-PEEM), we explore ultrafast microscopic imaging of SPP dynamics in nano-structured metals at 0.3-fs frame separation and 50-nm spatial resolution (Fig. 2).
Fig.2 Schematic of experimental setup for ITR-PEEM.
Excitation light is a second harmonic generation of Ti: sapphire laser oscillator at 10-fs pulse width and 400-nm center wavelength. Phase correlated pump-probe pulse pairs are prepared by splitting fs-pulses through a Mach-Zehnder interferometer. The delay time between pump and probe (τd) is controlled at an accuracy of <50-as (<1/25λ). The pump-probe excitation light is focused on a sample placed in a focal plane of PEEM to induce photoemission through a plasmon-enhanced two-photon photoemission process. Two-dimensional microscopic distribution of the photoemission current projected onto the PEEM screen reveals an intensity map of the internal electrical field of the sample.
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