Multi-µJ coherent extreme ultraviolet source generated from carbon using the plasma harmonic method.
We demonstrate intense high-order harmonic generation from plasma that is created from different carbon targets. We obtain high-order harmonic energy in the multi-microjoule range for each harmonic order from the 11th to the 17th harmonic. By analyzing the target morphology and the plasma composition, we conclude that the intense harmonics from the bulk carbon targets originate from nanoparticles target.
Wavelength tuning of highly stable high-order harmonics generated from carbon plasma
We demonstrate large, continuous redshift of high-order harmonics generated from carbon plasma. These harmoinics also have high intensity stability, with the harmonic yield only doubling when increasing the driving laser intensity by ten times.
Giant plasmon excitation in free C60 and C70 molecules studied by photoionization.
Single-photon ionization of ${\mathrm{C}}_{60}$ and ${\mathrm{C}}_{70}$ has been studied using synchrotron radiation in an energy range from the ionization potential (7.54\ifmmode\pm\else\textpm\fi{}0.04 eV for ${\mathrm{C}}_{60}$ 7.3\ifmmode\pm\else\textpm\fi{}0.2 eV for ${\mathrm{C}}_{70}$) up to 35 eV. The photoion yield is dominated by a strong resonance at about 20 eV with a FWHM of \ensuremath{\sim}10 eV. We interpret this as being due to autoionization via the giant plasmon resonance recently predicted in the RPA approximation. ${\mathrm{C}}_{60}$ and ${\mathrm{C}}_{70}$ offer the unique possibility for a quantitative comparison of this collective excitation in the free molecule with that observed in the solid phase by electron-energy-loss spectroscopy at about 28 eV.