A laser-based system to allow the temporal evolution of plasmonic fields on surfaces
with attosecond resolution is presented.
Sub 7fs carrier envelope phase stabilised infra-red (IR) pulses with 450μJ have
been generated using a hollow fiber compression system utilising self phase modulation
to produce a 400nm FWHM bandwidth centred at 790nm and subsequent
compression with chirped mirrors.
The isolated attosecond pulse was produced using spectra selection of a continuum
of extreme ultraviolet (XUV) photons generated from a single half cycle emission
from the IR driving field. The isolated XUV was characterised using the atomic
streak camera technique and a pulse duration of 270as was retrieved using a frequency
resolved optical gating algorithm.
An ultra high vacuum (10⁻¹⁰mbar) surface science system for attosecond pump-probe
studies of surfaces was designed and built, connecting directly to the attosecond
beamline. A sample manipulator was developed to precisely position surface
samples in the IR and XUV foci. Novel vibrational decoupling mechanisms were
developed, achieving only 10nm of motion measured of the sample head.
An electron spectrometer with a resolution of 0.05eV for 30eV was used to measure
localised nanoplasmonic intensity enhancement of 10³ from a rough silver surface
(4mm RMS roughness) by collecting 35eV photoelectrons emitted by a few-cycle
IR field with an intensity of ~10¹⁰W/cm².
A 2-photon photoemission XUV-IR cross correlation measurement probing hot
electron dynamics in a gold surface is reported, revealing femtosecond dynamics
of electron thermalisation.