The rapid development of near‐infrared (NIR) spectroscopic techniques has greatly stimulated the discovery of novel broadband NIR‐emitting phosphors as advanced light sources. Herein, a novel double‐perovskite phosphor La2MgHfO6:Cr3+/Yb3+ that displays ultra‐broadband NIR emissions with a full‐width at half maximum (FWHM) of 333 nm is reported. The remarkable luminescence property stems from the multiple crystallographic sites, relatively weak crystal field, and efficient Cr3‐to‐Yb3+ energy transfer (ET). The site occupation of Cr3+ is elaborately verified by the Rietveld refinement and first‐principles calculation. By controlling the ET process, the internal/external quantum efficiency (IQE/EQE), bandwidth, and thermal stability of NIR emissions are substantially improved. The as‐prepared phosphors are further integrated into a miniaturized NIR light‐emitting diode (LED) package, demonstrating superior performance in rapid nondestructive detection of structural failure in thin electronic cables. The results described here provide a novel pointcut for designing broadband NIR‐emitting phosphors with desired optical properties toward applications in industrial inspection and medical diagnosis.
Near-infrared laser provides a novel nerve stimulation modality to regulate the cell functions. Understanding its physiological effect is a prerequisite for clinic laser therapy applications. Here, the whole-cell sodium (Na) channel kinetics of neuron cell was employed to determine the temporal roles of infrared laser. The Na currents were elicited by electrical pulses that were synchronized at the rising and falling edges of the 980 nm laser pulses, respectively, to investigate the different infrared effect on cell functions. The time constants of activation (τ(m)) and inactivation (τ(h)) kinetics were extracted from fitting of the Na current (m(3)h) according to the Hodgkin-Huxley (HH) model. By comparing the time constants without and with the laser irradiation, we obtained that laser pulses changed the Na current kinetics by accelerating τ(h)-phase and slowing down τ m-phase at the beginning of the laser pulse, whereas both phases were accelerated at the end of the pulse. After relating the ratios of the time constants to the temperature characteristics of Na channel by Q10, we found that the accelerating in Na current kinetics could be related to the average temperature of extracellular solution in the corresponding time span by choosing Q10 = 2.6. The results of this study demonstrated that there was a positive correlation between the acceleration of the Na current kinetics and increases in temperature of the extracellular solution.
Photothermal effect has been proved to mediate the interaction of near-infrared laser with biological tissue. However, the generation and transformation mechanism of the photothermal effect is still unclear. In this paper, we combine a patch clamp technique with the laser simulation to figure out the chromophores, which are responsible for the photothermal effect generation. This method is based on the fact that temperature dependence of solution can be measured as resistance changes. A dual-wavelength infrared light irradiating the open pipette in extracellular solution is designed to study the relation between the photothermal effect and the absorption property of solution. The principle is based on that the nearly ten times difference in the magnitude of the optical absorption coefficient in water (0.502 cm-1 at 980 nm and 0.0378 cm-1 at 845 nm), makes the corresponding proportional absorption-driven temperature rise. The photothermal effect in laser-tissue interaction can be assessed in two stages: the establishment and the dissipation of the temperature rise. In the establishment stage, an open pipette method is employed to measure the temperature rise by fabricating a glass pipette which is filled with electrolyte solution. In the dissipation stage, the electrophysiological function of a living neuron cell is studied based on a patch clamp. Theoretical calculation and experimental results show that the optical absorption properties of solution determine the photothermal effect. The results can be used to study the photothermal effect in laser-tissue interaction.
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