ABSTRACT
Recently, low-dimensional copper(I)-based perovskite or derivatives have gained extensive attention in scintillator applications because of their environmental friendliness and good stabilities. However, the unsatisfactory scintillation performance and complex fabrication processes hindered their practical applications. Herein, efficient yellow emissive CsCu2I3 nanocrystals (NCs) were successfully prepared via a simple Mn2+-assisted hot-injection method. The added Mn2+ effectively induced the phase transformation from Cs3Cu2I5 to CsCu2I3, leading to the preparation of single-phase CsCu2I3 NCs with few defects and a high fluorescence performance. The as-prepared "optimal CsCu2I3 NCs" exhibited superior photoluminescence (PL) performance with a record-high PL quantum yield (PLQY) of 61.9%. The excellent fluorescence originated from the radiative recombination of strongly localized one-dimension (1D) self-trapped excitons (STEs), which was systematically investigated via the wavelength-dependent PL excitation, PL emission, and temperature-dependent PL spectra. These CsCu2I3 NCs also exhibited outstanding X-ray scintillation properties with a high light yield (32000 photons MeV-1) and an ultralow detection limit (80.2 nGyair s-1). Eventually, the CsCu2I3 NCs scintillator film achieved an ultrahigh (16.6 lp mm-1) spatial resolution in X-ray imaging. The CsCu2I3 NCs also exhibited good stabilities against X-ray irradiation, heat, and environmental storage, indicating their great application potential in flexible X-ray detection and imaging.
ABSTRACT
LiBaPO4:Eu2+ phosphor and Ag-coated LiBaPO4:Eu2+ composites (Ag/LiBaPO4:Eu2+) were prepared via solid-state reaction and traditional photoreduction methods, respectively. The samples were characterized via XRD, SEM, and UV-vis optical absorption spectroscopy. Two photoenergy conversion processes, namely, photocatalysis and photoluminescence, were investigated in detail. In comparison with as-prepared LiBaPO4:Eu2+ phosphor, Ag-modified composites exhibited the enhanced photocatalytic effects together with the quenched Eu2+ luminescence. A Schottky barrier was created on the interface between Ag nanoparticles and LiBaPO4 host, thereby greatly delaying the recombination between the light-induced holes and electrons. A photoenergy conversion mechanism was suggested and discussed on the basis of the experiments. The Eu2+ ion luminescence centers directly participated in the photodegradation with the meditation of Ag nanoparticles on the surface. With the increase of the Ag coating level on the surfaces, some emission peaks corresponding to 5D0 â 7F0,1,2,3,4 transitions of Eu3+ ions were detected. Eu2+/Eu3+ couples also play an important role in improving photocatalysis. LiBaPO4:Eu2+ phosphor is a good candidate for the investigation of multimodal photoenergies of photoluminescence and photocatalysis.
ABSTRACT
We report on an experimental and theoretical study of a large-aperture Ti:Sapphire (Ti:S) amplifier pumped with a novel temporal dual-pulse scheme to suppress the parasitic lasing (PL) and transverse amplified spontaneous emission (TASE) for high-energy chirped-pulse amplification (CPA). The pump energy distribution was optimized and the time delay between each pump pulse was controlled precisely. Both the numerical and experimental results confirm that the temporal dual-pulse pump technique can effectively suppress PL and TASE. The maximum output energy of 202.8 J was obtained from the final 150-mm-diameter Ti:S booster amplifier with a pump energy of 320.0 J, corresponding to a conversion efficiency of 49.3%. The compressed pulse duration of 24.0 fs was measured with a throughput efficiency of 64%, leading to a peak power of 5.4 PW. This novel temporal dual-pulse pump technique has potential applications in a 10 PW CPA laser system.
