【摘要】 通过测量叶绿素a苯溶液中加入溶胶-凝胶法制备的氧化锌纳米粒子后的紫外-可见吸收光谱、荧光光谱的变化,研究得出两者通过静电作用相结合,而且由于氧化锌的导带顶低于叶绿素a的第一激发态能级,所以能够产生界面电荷转移,表现在叶绿素a溶液的特征吸收峰在加入纳米粒子后峰位向长波方向移动。用355nm波长的光激发该样品得到的荧光光谱在654nm处出现一个等发射点,并且随着氧化锌量的增多叶绿素a溶液的发光被猝灭且峰位向长波方向移动,当用433nm波长的光激发时(氧化锌在此波长下没有吸收),没有等发射点但仍有猝灭和峰位移动现象,其中猝灭现象根据Stern-Volmer关系可归结为静态猝灭。另外,向离心后得到的氧化锌纳米粒子粉末中滴加叶绿素a,发现在滴加前后其红外光谱中Zn—O键的振动峰发生变化,说明氧化锌纳米颗粒与叶绿素a分子之间存在一定的相互作用,并且可能对叶绿素光合作用产生一定负面影响。更多还原

【Abstract】 The influence of ZnO nanoparticles on chlorophyll a (Chl-a) was studied by observing their absorption, fluorescence, and Fourier transform infrared spectra (FTIR). Chl-a molecules were absorbed onto the surface of the colloidal nanoparticles due to the electrostatic interactions between Chl-a molecules and particle surfaces which led to a redshift of the absorption peaks of Chl-a upon addition of ZnO nanoparticles to Chl-a benzene solution. The redshift of the fluorescence spectra and the quenching of the fluorescence emission of Chl-a suggested a charge-transfer between Chl-a and ZnO nanoparticles. The difference between the first exci-ted state of Chl-a and the bottom of the conduction band of ZnO may provide the necessary driving force for such a charge-transfer process. An isoemissive point was observed at 654 nm in the fluorescence spectra when excited by 355 nm. No isoemissive point was found when excited by 433 nm, because ZnO nanoparticles have no absorption at this wavelength. Based on the Stern-Volmer relation I0/I=1+K[Q], the quenching mechanism was attributed to static quenching. Besides, changes of Zn—O bond vibration peak in FTIR were also observed after the Chl-a molecules were absorbed onto ZnO nanoparticles. The above studies illustrated a strong interaction between Chl-a and ZnO nanoparticles, and indicated that ZnO nanoparticles may exert negative impact on the photosynthesis process, where Chl-a plays an important role.更多还原