Combined Effect of Uniaxial Strain and Magnetic Field on the Exciton States in Semiconducting Single-Walled Carbon Nanotubes

The exciton states of semiconducting carbon nanotubes are calculated by a tight-binding model supplemented by Coulomb interactions under the combined effect of uniaxial strain and magnetic field. It is found that the excitation energies and absorption spectra of zigzag tubes（11,0） and（10,0） show opposite trends with the strain under the action of the magnetic field. For the（11,0） tube, the excitation energy decreases with the increasing uniaxial strain, with a splitting appearing in the absorption spectra. For the（10,0） tube, the variation trend firstly increases and then decreases, with a reversal point appearing in the absorption spectra. More interesting,at the reversal point the intensity of optical absorption is the largest because of the degeneracy of the two bands nearest to the Fermi Level, which is expected to be observed in the future experiment. The similar variation trend is also exhibited in the binding energy for the two kinds of semiconducting tubes.

Strong coupling between a plasmon mode and multiple different exciton states

Strong coupling between plasmons and multiple different exciton states(MESs)enables the creation of multiple hybrid polariton states under ambient conditions.These hybrid states possess unique optical properties different from those of their separate identities,making them ideal candidates for exploiting room-temperature multimode hybridization and multiqubit operation.In this study,we revealed the static spectral response properties of plasmon-MES strong coupling via a fully quantum mechanics approach.These theoretical predictions were experimentally demonstrated in plasmonic nanocavities containing two and three different exciton species.Additionally,the dynamical absorption processes of such strong coupling systems were investigated,and results indicated that the damping of the hybrid polariton states induced by the strong coupling could be markedly modulated by the acoustic oscillations from the plasmonic nanocavities.Our findings contribute a theoretical approach for accurately describing the plasmon-MES interactions and a platform for developing the high-speed active plasmonic devices based on multiqubit strong coupling.

Au cluster anchored on TiO_(2)/Ti_(3)C_(2) hybrid composites for efficient photocatalytic CO_(2) reduction

The size of metal nanoparticles is a key factor to enhance the photocatalytic activity of photocatalysts.However,the mechanism of this factor to the improvement of photocatalytic CO_(2) reduction performance is still unclear.Here,Au cluster/TiO_(2)/Ti_(3)C_(2) and Au nanoparticle/TiO_(2)/Ti_(3)C_(2) were successfully prepared by deposition-precipitation method.The experimental results show that the photocatalytic CO_(2) reduction performance of Au cluster/TiO_(2)/Ti_(3)C_(2) with quantum size effect is stronger than that of Au nanoparticle/TiO_(2)/Ti_(3)C_(2) with surface plasmon resonance.The enhanced photocatalytic CO_(2) reduction activity is assigned to the establishment of an overlapping orbital between the lowest unoccupied molecular orbital(LUMO)of the Au cluster and the anti-bonding orbital of CO_(2),which greatly promotes the activation efficiency of CO_(2).The existence of Au cluster and the mechanism of photocatalytic CO_(2) reduction performance were certified by high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)and in situ Fourier transform infrared spectroscopy(ISFTIR).This work may open new opportunities for the establishment of stable and active metal nanocatalysts.