13,453 research outputs found
Valley Carrier Dynamics in Monolayer Molybdenum Disulphide from Helicity Resolved Ultrafast Pump-probe Spectroscopy
We investigate the valley related carrier dynamics in monolayer MoS2 using
helicity resolved non-degenerate ultrafast pump-probe spectroscopy at the
vicinity of the high-symmetry K point under the temperature down to 78 K.
Monolayer MoS2 shows remarkable transient reflection signals, in stark contrast
to bilayer and bulk MoS2 due to the enhancement of many-body effect at reduced
dimensionality. The helicity resolved ultrafast time-resolved result shows that
the valley polarization is preserved for only several ps before scattering
process makes it undistinguishable. We suggest that the dynamical degradation
of valley polarization is attributable primarily to the exciton trapping by
defect states in the exfoliated MoS2 samples. Our experiment and a
tight-binding model analysis also show that the perfect valley CD selectivity
is fairly robust against disorder at the K point, but quickly decays from the
high-symmetry point in the momentum space in the presence of disorder.Comment: 15 pages,Accepted by ACS Nan
Root Pose Decomposition Towards Generic Non-rigid 3D Reconstruction with Monocular Videos
This work focuses on the 3D reconstruction of non-rigid objects based on
monocular RGB video sequences. Concretely, we aim at building high-fidelity
models for generic object categories and casually captured scenes. To this end,
we do not assume known root poses of objects, and do not utilize
category-specific templates or dense pose priors. The key idea of our method,
Root Pose Decomposition (RPD), is to maintain a per-frame root pose
transformation, meanwhile building a dense field with local transformations to
rectify the root pose. The optimization of local transformations is performed
by point registration to the canonical space. We also adapt RPD to multi-object
scenarios with object occlusions and individual differences. As a result, RPD
allows non-rigid 3D reconstruction for complicated scenarios containing objects
with large deformations, complex motion patterns, occlusions, and scale
diversities of different individuals. Such a pipeline potentially scales to
diverse sets of objects in the wild. We experimentally show that RPD surpasses
state-of-the-art methods on the challenging DAVIS, OVIS, and AMA datasets.Comment: ICCV 2023. Project Page: https://rpd-share.github.i
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