Control of the electron dynamics in solid-state high harmonic generation on ultrafast time scales by a polarization-skewed laser pulse.

Since high-order harmonic generation (HHG) from atoms depends sensitively on the polarization of the driving laser field, the polarization gating (PG) technique was developed and applied successfully to generate isolated attosecond pulses from atomic gases. The situation is, however, different in solid-state systems as it has been demonstrated that due to collisions with neighboring atomic cores of the crystal lattice strong HHG can be generated even by elliptically- and circularly-polarized laser fields. Here we apply PG to solid-state systems and find that the conventional PG technique is inefficient for the generation of isolated ultrashort harmonic pulse bursts.

Graphene quantum dots, graphene oxide, carbon quantum dots and graphite nanocrystals in coals.

Six coal samples of different ranks have been used to prepare single-layer graphene quantum dots (S-GQDs). After chemical oxidation and a series of centrifugation separation, every coal could be treated into two fractions, namely, CoalA and CoalB. According to the characterization results of TEM, AFM, XRD, Raman and FTIR, CoalA was revealed to be mainly composed of S-GQDs, which have an average height of about 0.

Electrochemiluminescence of water-soluble carbon nanocrystals released electrochemically from graphite.

Water-soluble carbon nanocrystals (CNCs) with electrochemiluminescence (ECL) activity were released into aqueous solution from a graphite rod by applying a scanning potential. ECL emission of CNCs observed during their preparation probably provides a useful method for monitoring and screening nanocrystal preparation. The ECL behavior and its mechanism in CNCs have been studied in detail for the first time.