II–VI
two-dimensional (2D) nanoplatelets (NPLs) exhibit
the narrowest optical features among nanocrystals (NCs). This property
remains true for Hg-based NPLs, despite a cation exchange procedure
to obtain them from Cd-based NPLs, which leads to structural defects
(poorly defined edges and voids) inducing inhomogeneous broadening.
Here, we propose an optimized procedure for which a solvent, surface
chemistry, and reaction conditions are rationally considered. The
procedure is applied to the growth of alloyed HgSe1–x
Te
x
NPLs with various
compositions. We report a bright photoluminescence for all compositions.
Structural properties being now well defined, it is possible to study
the electronic properties of these objects. To do so, we combine k·p
modeling of quantum-confined structures with X-ray photoemission.
In particular, we clarify the origin of the similarity between CdTe
and HgTe NPLs absorption spectra despite their vastly differing bulk
band structures. Finally, static- and time-resolved photoemission
unveil a crossover from n- to p-type behavior in HgSe1–x
Te
x
NPLs while increasing
the Te content.
We report on the performances of the mode locking of a flash-lamp-pumped Nd:YAG laser using a frequency-doubling nonlinear mirror combined with a two-photon absorber. Pulse lengths from 12 to 8 ps are generated. We show that the flat shape of the pulse-train envelope generated by the oscillator is adapted for the synchronous pumping of optical parametric oscillators and we demonstrate the efficient generation of an infrared beam tunable from 3800 to 1100 cm−1 with bandwidth of 2 cm−1 in one single conversion stage in LiNbO3 or AgGaS2. The “all-solid-state” laser system enables surface sum-frequency generation spectroscopy to be performed with high sensitivity and high resolution.
Efficient mode locking of a flash-lamp-pumped Nd:YAG laser at 1.064 μm is achieved by combining the passive–positive feedback of a frequency doubling nonlinear mirror (FDNLM) and the passive–negative feedback of a GaAs platelet. the FDNLM consists of a BBO crystal and of a dichroïc mirror. Pulse durations as short as 12 ps are obtained. Temporal evolution of pulse duration in the pulse train is presented and discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.