Unusual Pressure-Induced Self-Trapped Exciton to Free Exciton Transfer in Chiral 2D Lead Bromide Perovskites.

The phenomenon of pressure-induced emission alterations related to complex excitonic dynamics in 2D lead halide perovskites (LHPs) has gained considerable attention for understanding their structure-property relationship and obtaining inaccessible luminescence under ambient conditions. However, the well-known pressure-induced emissions are limited to the formation of self-trapped excitons (STEs) due to the structural distortion under compression, which goes against the advantage of the highly pure emission of LHPs. Here, the pressure-induced detrapping from STEs to free excitons (FEs) accompanied by the dramatic transition from broadband orangish emission to narrow blue emission has been achieved in chiral 2D LHPs and - and -[4MeOPEA]PbBr, (4MeOPEA = 4-methoxy-α-methylbenzylammonium).

Phase transition of Mg(PO) polymorphs at high-temperature: In-situ synchrotron X-ray diffraction and Raman spectroscopic study.

In-situ synchrotron X-ray diffraction and Raman spectroscopy were used to study the stabilities, thermal expansion and vibrational modes of synthetic Mg(PO). The polymorphs (Mg(PO)-I, II, III) were investigated in the temperature range of 299 ∼ 1173 K at ambient pressure. An irreversible phase transition was observed for both Mg(PO)-II and Mg(PO)-III, whereas Mg(PO)-I is stable in the present study.

Pressure-Induced Phase Transition in Mn(Ta,Nb)O: An Experimental Investigation and First-Principle Study.

The high-pressure and high-temperature behaviors of manganotantalite Mn(Ta,Nb)O have been investigated by single-crystal X-ray diffraction and Raman spectroscopy combined with diamond anvil cell technique, as well as first-principle calculations. A pressure-induced reversible phase transition of manganotantalite occurs at 9.5 GPa and room temperature, accompanied by a large volume collapse (∼7.

Distance makes a difference in crystalline photoluminescence.

Crystallization-induced photoluminescence weakening was recently revealed in ultrasmall metal nanoparticles. However, the fundamentals of the phenomenon are not understood yet. By obtaining conformational isomer crystals of gold nanoclusters, we investigate crystallization-induced photoluminescence weakening and reveal that the shortening of interparticle distance decreases photoluminescence, which is further supported by high-pressure photoluminescence experiments.

Data for photoluminescence spectra of natural Cr-doped MgAlO spinel during order-disorder transition.

Photoluminescence (PL) spectra of natural Cr doped MgAlO spinel from Tanzania were taken during its order-disorder transition (ODT) process. Samples were changed their disordered degree by quenching treatment. PL spectra were taken at the liquid nitrogen (LN) temperature (∼77 K) using a 532 nm laser excitation.

Spectra and Mineralogy Study on Black Tianhuang and Kengtou Stone from Shoushan, Fujian Province.

Shoushan Stone is one of the national stones of our country which is also the most famous stone of the four outstanding seal stones in China. As to Shoushan stones, black Tianhuang stone is a kind of black colored stone. It is one of the most special species in Tianhuang stones which comes from fields beside the Shoushan Brook.

[Current quality management situation and administration countermeasure study of enterprises marketing corneal contact lens].

Objective: Study the current quality management situation of enterprises marketing corneal contact lens via systemic investigations and explore effective administration countermeasures in the future.

Methods: The quality management indicators of sixty-two corneal contact lens marketing enterprises in Xuhui district of Shanghai were systematically investigated and enterprises of different operation models was compared and analyzed.

Results: Wholesale enterprises and retail chain enterprises are apparently better than independent enterprises almost in all facets.

[Gemology and spectra characterization of gem garnet from Muling City, Heilongjiang Province].

Cenozoic basalts gem-garnets from Muling City, Heilongjiang Province were studied by using standard gemological methods, electron microprobe, Raman spectroscopy, infrared spectroscopy, and ultraviolet-visible spectroscopy to obtain the gemology and spectra characterization. Chemical composition analysis indicates that the garnets are pyropes with some impurity element Fe, Ca, Mn, Cr, and Ti. The average chemical structure formula of the gem-garnet is (Mn0.

[Mineralogical and spectral characteristics of copper pectolite].

Copper pectolite, a type of pectolite with blue stripes, is a rare gem material with a great market prospect. Mineralogy and genesis were investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR), Raman spectroscopy (Raman), scanning electron microscopes (SEM) and ultraviolet-visible spectrometer(UV-VIS) to understand the mineralogical compositions and characteristics of the parts with different color. XRD, FTIR and Raman result showed that copper pectolite is composed of pectolite and minor calcite, consistent with the result of SEM.

[Infrared and Raman spectra study on Tianhuang].

The Tianhuang stones, from Shoushan in China, were studied by using X-ray powder diffractometry (XRD), infrared (IR) spectroscopy and Raman spectroscopy to obtain the spectra characterization. Wave numbers 3621, 3629 and 3631 cm(-1) in the IR spectra and 3626, 3627 and 3632 cm(-1) in the Raman spectra are the characteristic peaks of dickitic Tianhuang, nacritic Tianhuang and illitic Tianhuang, respectively. Raman spectra assigned to OH are in good agreement with the IR results at 3550 -3750 cm(-1).