Abstract
The generation of coherent light pulses in the extreme ultraviolet
(XUV) spectral region with attosecond pulse durations constitutes the
foundation of the field of attosecond science [1]. Twenty years
after the first demonstration of isolated attosecond pulses [2], they
continue to be a unique tool enabling the observation and control of
electron dynamics in atoms, molecules and solids [3, 4]. It has long
been identified that an increase in the repetition rate of attosecond
light sources is necessary for many applications in atomic and
molecular physics [5, 6], surface science [7], and imaging
[8]. Although high harmonic generation (HHG) at repetition rates
exceeding 100 kHz, showing a continuum in the cut-off region of the
XUV spectrum was already demonstrated in 2013 [9], the number of
photons per pulse was insufficient to perform pulse characterisation
via attosecond streaking [10], let alone to perform a pump-probe
experiment. Here we report on the generation and full characterisation
of XUV attosecond pulses via HHG driven by near-single-cycle pulses at
a repetition rate of 100 kHz. The high number of 106 XUV photons per
pulse on target enables attosecond electron streaking experiments
through which the XUV pulses are determined to consist of a dominant
single attosecond pulse. These results open the door for attosecond
pump-probe spectroscopy studies at a repetition rate one or two
orders of magnitude above current implementations.
Generation and characterisation of isolated attosecond pulses at 100 kHz repetition rate