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From a copper target, laser-ablated plasma was investigated by spectral- and temporal-resolved emission spectroscopy. With the presence of a 0.8 T steady magnetic field, the emission of the expanding plasma showed significant enhancements of the spectral lines for all neutral, singly, and doubly ionized species. The relative enhancements for different species have been studied with temporal-resolved measurement by comparing the spectra obtained with and without the magnetic field. The enhanced emission from the plasma plume is attributed to an increase of the radiative recombination rate in the plasma due to magnetic confinement. The temporal evolution of the plasma parameters, including electron temperature and electron density, was deduced and discussed for the cases with and without a magnetic field. OCIS codes: 300.6365, 300.2140, 300.6350, 300.6320, 350.5400.

A comparative investigation on the photophysical properties of a quinoxaline derivative 4,4'-((1 E ,1' E )-quinoxaline-2,3-diylbis(ethene-2,1-diyl))bis( N , N -dimethylaniline) (QDMA2) was performed by employing many spectroscopies. Based on the pump-dump/push-probe measurement, it is found that a solvent-stabilized charge-transfer state can participate in the relaxation of excited QDMA2 with increasing solvent polarity. Meanwhile, the aggregated QDMA2 molecules were engineered into the organic light-emitting diode test, which showed a correlated color temperature value of 1875 K. With the help of a diamond anvil cell, the pressure-dependent photoluminescence of aggregated QDMA2 shows that the intermolecular interaction can affect the color and intensity of photoluminescence through adjusting the band gap and irradiative channel of the aggregated molecules. These results are important for understanding the structure-property relationships and the rational design of functional materials for optoelectronic applications.

It is important to determine the time-dependent evolution of the excited monolayer WS 2 , which will provide a basis for the reasonable design of optoelectronic devices based on two-dimensional transition metal dichalcogenides. Here, we made a simple and large-area photodetector based on the monolayer WS 2 , with high light sensitivity and fast response, benefiting from the special dynamics of carrier involving the exciton, trion, and charge. Moreover, we tested the relaxation behavior of the excited monolayer WS 2 by employing transient absorption (TA). It was found that the multi-body interaction among exciton would occur after the density of pump photon increases to 3.45 × 10 14 photons per cm 2 . The exciton dissociation accompanying the generation of trion would appear in the photo-induced relaxation process, which would be a benefit for the operation of this photodetector. Increasing the energy of the exciton is good for the generation of carrier by comparing the relaxation behavior of WS 2 excited to A and B exciton states. However, the bound exciton relaxation, originating from the capture process of the defect state, would exist and play an unfavorable role during the functioning of devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)