Vibrational properties of ultrathin PTCDA films on Ag(110)
Vibrational properties of ultrathin PTCDA films on Ag(110)
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Ag(110) 超薄 PTCDA 薄膜的振动特性
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
E. Umbach
中科院分区：
文献类型：
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作者：
F. Tautz;S. Sloboshanin;J. Schaefer;R. Scholz;V. Shklover;M. Sokolowski;E. Umbach
利用高分辨电子能量损失谱（HREEL）和傅里叶变换红外光谱（FTIR）研究了3，4，9，10-二萘嵌苯四甲酸二酐（PTCDA）在Ag（110）表面的沉积。X射线光电子能谱，低能电子衍射（LEED），和四极质谱被用来控制真空升华PTCDA膜的厚度，成分和顺序。利用HREELS的高表面灵敏度，可以清楚地区分与表面直接结合接触的分子与PTCDA环境中的分子，因为光谱显示前者分子的振动线的差分峰位移。为了帮助解释的光谱，离散傅里叶变换计算的振动频率的自由分子进行。的结果是在良好的协议与多层膜中的分子的实验值，并允许大多数的实验模式的识别，如果考虑到从非镜面HREELS测量的实验信息。通过计算的频率谱与FTIR数据的比较，可以提取分子间相互作用对振动光谱的影响。
We have investigated 3,4,9,10-perylene-tetracarboxylic acid-dianhydride (PTCDA) films on the Ag(110) surface by High-resolution electron energy loss (HREEL) and Fourier transform infrared (FTIR) spectroscopy. X-ray photoemission spectroscopy, low-energy electron diffraction (LEED), and quadrupole mass spectroscopy were used to control thickness, composition, and order of the vacuum-sublimated PTCDA films. Taking advantage of the high surface sensitivity of HREELS, it is possible to clearly distinguish molecules in direct binding contact to the surface from those being in a PTCDA environment, because the spectra show differential peak shifts of the vibrational lines for the former molecules. To aid the interpretation of the spectra, discrete Fourier transform calculations of the vibrational frequencies of the free molecule were carried out. The results are in good agreement with the experimental values for the molecules in the multilayer and allow the identification of most of the experimental modes, if experimental information from off-specular HREELS measurements is taken into account. By the comparison of the calculated frequency spectrum with FTIR data it is possible to extract the effects of the intermolecular interaction on the vibrational spectra.