酞菁镍与表面吸附氧和吡啶之间的电荷转移研究

A Study of Charge Transfer Between NiPc and Surface-Adsorbed Oxygen and Pyridine

利用表面光电压谱研究了酞菁镍的光伏性质及其受吸附O_2和吡啶的影响.在真空条件下,除观察到酞菁镍在335、650和580 nm附近有3个强光伏响应带外,还首次利用这一技术发现了450 nm附近有一弱光伏响应带,并指认该带为由中心金属Ni^(2+)的dπ轨道向酞菁环上的e_n(π~n)轨道的MLCT跃迁.在氧的存在下,450nm响应带会消失甚至发生反转,而吡啶的吸附则使酞菁镍的所有光伏响应带消失,但未观察到反转现象.

In this paper, the effects of adsorption of O2 and pyridine on the photovoltaic properties of NiPc was studied by surface photovoltage spectroscopy. A very weak photovoltaic response band near 450 nm was observed for the first time besides three strong bands near 335, 580 and 650 nm(B band and Q band), and was assigned to the charge transfer transition from the dπ orbital of central metal ion Ni2+ to the eg(π) orbital of PC ring. In the presence of O2, the three strong bands slightly decreased in intensity, but the weak band disappeared and even reversed. Unlike O2, the adsorption of pyridine can make all photovoltaic response bands of NiPc disappear, but no reversed band was observed. The above results show the charge transfer interaction between NiPc and surface electron acceptors.