Journal of Luminescence最新文献

The photochemical and photophysical properties of the new ligand N-[2-(5,6-dihydrobenzimidazo[1,2-c]quinazoline-6-yl)phenyl]-4-methylbenzolsulfamide (1) and its zinc complexes, namely [2-[(E)-[2-(1H-benzimidazol-2-yl)phenyl]iminomethyl]-N-(p-tolylsulfonyl)anilino]chloro-zinc (3) and acetoxy-[2-[(E)-[2-(1H-benzimidazol-2-yl)phenyl]iminomethyl]-N-(p-tolylsulfonyl)anilino]zinc (4) were studied using UV spectroscopy, time-resolved luminescence and stationary photolysis. Compound 1 combines the properties of Schiff bases and benzimidazole derivatives, both known as good luminophores. The structures of compounds in the crystalline state were determined by means of XRD. Ligand 1 demonstrates high photoluminescence quantum yields (PLQY) in solutions, while for the soluble zinc complex 3 it drops in an order of magnitude. PLQY in the solid state for all the compounds are moderate (0.2–0.3). For complex 3 the PLQY in the solid state is ca. 3 times higher than in solutions, demonstrating the effect of aggregation-induced enhancement of luminescence. The approach based on combining properties of the two classes of luminophores seems prospective for further development of luminescent materials.

Yellow phosphorescence emission of 1,8-naphthalimide guest was activated by doping it into m-bromobenzaldehyde host (energy transfer mechanism). With the aim of alleviating the triplet-triplet annihilation of the benzaldehyde itself, m-dibromobenzene was introduced as the third component. As a result, the phosphorescence quantum yields of the doped crystallized materials significantly increase from 1.72 % for NI@mBA to 19.17 % for NI@mBA@mDBB (with 11 times enhancement) due to the cascade activation in the three-component system. The encryption/decryption using these phosphorescent doped materials provides potential application in security field. This study not only expands the scope of organic host molecules capable of activating the phosphorescence properties of NI, but also provides a platform for developing multi-component organic doping systems that can effectively regulate phosphorescence properties.

It has been shown that the sensitization scheme involving non-radiative energy transfer from Tb³⁺ to Nd³⁺ in selenide glass is suitable for pumping a mid-infrared Nd³⁺ ion laser. Stimulated emission corresponding to a novel laser transition ⁴I_11/2–⁴I_9/2 of Nd³⁺ ions was demonstrated at liquid nitrogen temperature. Using an intracavity CaF₂ prism, the laser was tunable from 5.56 to 6.01 μm. Output energy up to 16 mJ has been obtained.

The ratiometric luminescent thermometry based on dual-emission centers can effectively overcome the limitations of temperature sensing based on thermally coupled levels. Herein, Bi³⁺ and Pr³⁺ co-doped CaNb₂O₆ phosphors were prepared by high-temperature solid-phase reactions, and crystal structural and photoluminescence were characterized. Then the luminescent thermometric properties of the obtained samples were studied, and the maximum absolute and relative sensitivity of the optimal sample (CaNb₂O₆: 0.5%Bi³⁺/0.5%Pr³⁺ phosphor) achieved are 0.09 K⁻¹ @ 528 K and 2.17 % K⁻¹ @ 453 K, respectively. Furthermore, the luminescence of CaNb₂O₆: 0.5%Bi³⁺/0.5%Pr³⁺ phosphor transforms remarkably from blue to red as the temperature rises, which can be adopted to monitor the ambient temperature via the glow color of the phosphor. To sum up, Bi³⁺ and Pr³⁺ co-doped CaNb₂O₆ phosphors have been shown to have good thermosensitive and thermochromic characteristics.