Determining the Dipole Orientation of Second Harmonic Generation in 3R-MoS for Enhanced Nonlinear Susceptibility.

As an efficient two-dimensional nonlinear optical crystal, 3R-MoS exhibits intrinsic bulk second-order nonlinearity with substantial second harmonic generation (SHG) due to the interfacial charge transfer induced interlayer dipole and intralayer intrinsic asymmetric dipole. However, how these dipoles determine the SHG emission dipole orientation and intensity in 3R-MoS has not been clearly resolved. Here, we accurately determine the coexistence of in-plane and out-of-plane SHG emission dipoles in few-layer 3R-MoS through radial-/azimuthal-polarization excitation SHG measurements and back focal plane (BFP) imaging combined with numerical simulations, where the SHG emission dipole orientation () in real space for 3L, 4L, 5L, and 6L 3R-MoS is determined to be ∼8°, ∼16°, ∼20°, and ∼32°, respectively.

Full phenology cycle carbon flux dynamics and driving mechanism of Moso bamboo forest.

Introduction: Moso bamboo forests, widely distributed in subtropical regions, are increasingly valued for their strong carbon sequestration capacity. However, the carbon flux variations and the driving mechanisms of Moso bamboo forest ecosystems of each phenology period have not been adequately explained.

Methods: Hence, this study utilizes comprehensive observational data from a Moso bamboo forest eddy covariance observation for the full phenological cycle (2011-2015), fitting a light response equation to elucidate the evolving dynamics of carbon fluxes and photosynthetic characteristics throughout the entire phenological cycle, and employing correlation and path analysis to reveal the response mechanisms of carbon fluxes to both biotic and abiotic factors.

Increased conductance of individual self-assembled GeSi quantum dots by inter-dot coupling studied by conductive atomic force microscopy.

The conductive properties of individual self-assembled GeSi quantum dots (QDs) are investigated by conductive atomic force microscopy on single-layer (SL) and bi-layer (BL) GeSi QDs with different dot densities at room temperature. By comparing their average currents, it is found that the BL and high-density QDs are more conductive than the SL and low-density QDs with similar sizes, respectively, indicating the existence of both vertical and lateral couplings between GeSi QDs at room temperature. On the other hand, the average current of the BL QDs increases much faster with the bias voltage than that of the SL QDs does.