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本文通过湿法化学还原法合成了平均粒径为4.42nm、标准差为0.98nm的球形银纳米颗粒,并研究了在不同反应时间后获得的银纳米颗粒对PVP和Alq3的荧光猝灭效应。通过深入研究发现,PVP的荧光猝灭效应主要由于其分子链上的酮基与Ag颗粒之间发生了静电吸附,进而导致处在激发态的PVP分子与银颗粒之间产生电子或者能量转移(即非辐射弛豫),猝灭了PVP的荧光发光;而Alq3的荧光猝灭效应则主要归因于银纳米颗粒的欧姆损耗。通过采用时域有限差分法进行模拟发现,溶液中随机分布的银纳米颗粒,不仅能够吸收激发电磁波,削弱激发场强度,而且能够吸收荧光分子辐射的电磁波,进而猝灭了Alq3分子的荧光效应。这些研究成果将有利于了解金属纳米颗粒与PVP及Alq3分子荧光发光之间的关系,为调控荧光发光提供指导。
In this paper, spherical silver nanoparticles with an average particle size of 4.42 nm and a standard deviation of 0.98 nm were synthesized by wet chemical reduction method. The fluorescence quenching effects of silver nanoparticles on PVP and Alq3 were also studied after different reaction time. Through further study, we found that the fluorescence quenching effect of PVP is mainly due to the electrostatic adsorption between the ketone groups and Ag particles in the molecular chain, which leads to the electron or energy transfer between the PVP molecules and silver particles in the excited state That is, non-radiative relaxation), quenching the fluorescence of PVP; and the fluorescence quenching effect of Alq3 is mainly due to the ohmic loss of silver nanoparticles. Through the simulation using time-domain finite difference method, it is found that silver nanoparticles randomly distributed in solution can not only absorb excitation electromagnetic wave and weaken the excitation field, but also absorb the electromagnetic wave radiated by the fluorescent molecule, thereby quenching the fluorescence effect of the Alq3 molecule. These findings will help to understand the relationship between metal nanoparticles and PVP and Alq3 molecular fluorescence and provide guidance for the regulation of fluorescence emission.