纯度为9.75%的有机半导体材料苝四甲酸二酐(PTCDA),在其升华点进行了真空升华提纯,其纯度可达99.9%.利用质谱、红外光谱及X光电子能谱对这种高纯材料进行了测试并详细分析了其分子结构、化学键的形成、原子在晶格平衡位置的振动模式、电子的组态和原子的结合能的变化.由红外光谱分析得出,苝四甲酸二酐的分子结构是中央5个C构所组成的苝核基团及位于苝核两端的两个酸酐组成,它们主要以共价键结合.晶格上的C原子在其平衡位置主要以伸缩振动为主.其分子中有大量可以自由移动的π电子;分子间离域大π键的交叠决定了苝四甲酸二酐的导电性能.由XPS谱分析得出,高纯度的苝四甲酸二酐中有结合能不同的两种C原子,结合能分别为:285.3和288.7　eV.它们对应于苝环及酸酐上的C原子.另外,有两种类型的O原子,即CO和C—O—C,其结合能分别为531.3和533.1　eV。

The organic semiconductor 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) with the purity of 97.5% was purified by sublimation to 99.9%.The high-purity PTCDA material was measured by mass spectra,infrared spectrum and X-ray photoelectron spectroscopy (XPS).Detailed analysis revealed its molecular structure,the forming of chemical bond,the vibration modes of atoms in equilibrium lattice position,electronic configuration and the shift of binding energy of atoms.Based on the infrared spectrum analysis,the molecular structure of PTCDA is consisting of perylene core group with five C rings and two anhydrides located at both ends of perylene core,which is mainly bonded with covalent bond.The stretching vibration of C atoms in the crystal lattice dominates in their equilibrium positions.The PTCDA molecules have a large number of π electrons which can move freely;the intermolecular delocalized π bond overlap determines the conductivity of PTCDA.Based on XPS analysis,it can be found that there exist two kinds of C atoms with different binding energy:285.3 and 288.7 eV,respectively,corresponding to the C atoms in the perylene ring and anhydride.In addition,there are two kinds of O atoms,i.e.COand C—O—C,whose bonding energy is 531.3 and 533.1 eV,respectively.