Attosecond Technology - Light Sources,  Metrology, Applications
 
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The Project
• Light sources
• Metrology
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Recent News
• Invited article on cover of Review of Scientific Instruments
• Imperial attosecond streaking measurement on the cover of J. Phys. B. Special Issue
• Attosecond public engagement at the Imperial College Festival
• Can we freeze time? - John tisch's Inaugural Lecture
• Numerical simulation of attosecond nanoplasmonic streaking
• Later Shearing Interferometry of High-Harmonic Wavefronts
• Measurement of a sub-4fs high energy pulse.
• First isolated attosecond pulses measured in the UK

Molecular Experiments

Contents

 

Instrument development:

  • An attosecond streak camera based on a high-resolution retarding time-of-flight (TOF) electron spectrometer has been built.
  • An experimental chamber with two ion TOF spectrometers for demonstration experiments has been completely refurbished. Special, high-compression turbomolecular pumps have been installed to allow studies of molecular hydrogen. Computer-controlled gas handling system has been added.
  • A universal TOF data acquisition system has been implemented; it allows collection of multi-hit coincidence events at 1 kHz repetition rate.
  • A high-harmonic generation (HHG) source with interferometrically-controlled IR reference beam has been constructed. The source uses a novel way of recombining the extreme-ultraviolet (XUV) and IR beams developed in collaboration with the Saclay laboratory.
  • A magnetic-bottle electron spectrometer is being refurbished.
  • An XUV spectrometer with a CCD camera is being built.

 

Demonstration experiments:

  • Electron dynamics in krypton Rydberg states has been studied as a test trial of the instrumentation. To minimise the complexity of the setup the XUV pump-probe pulses were generated by splitting the generating IR pulses rather than the XUV ones. The experiment served its purpose, the instrumentation was performing according to the design, and interference fringes on the photoelectron spectra were observed. Unfortunately, the IR interference in the HHG process completely masked any quantum interference in krypton atoms. The experiments will be continued with a more sophisticated optical setup.
  • The dynamics of molecular hydrogen has been studied in IR and XUV fields combined with interferometric accuracy. The preliminary results are very encouraging. There is a clear signature of bond softening of the ground H2+ state under the influence of the IR field. As this state is created by the XUV pulses, the experiment allows us to separate the ionisation and dissociation processes. To get insight into the electron dynamics, the experiment requires characterisation of the XUV attosecond structure in parallel with experimental runs.