Johansson E M J, Hedlund M, Siegbahn H, Rensmo H
Department of Physics, Uppsala University, Box 530, SE-751 21 Uppsala, Sweden.
J Phys Chem B. 2005 Dec 1;109(47):22256-63. doi: 10.1021/jp0525282.
The element specificity of photoelectron spectroscopy (PES) has been used to compare the electronic and molecular structure of the dyes Ru(tcterpy)(NCS)3 (BD) and Ru(dcbpy)2(NCS)2 adsorbed from solution onto nanostructured TiO2. Ru(dcbpy)2(NCS)2 was investigated in its acid (N3) and in its 2-fold deprotonated form (N719) having tetrabutylammonium (TBA+) as counterions. A comparison of the O1s spectra for the dyes indicates that the interactions through the carboxylate groups with the TiO2 surface are very similar for the dyes. However, we observe that some of the dye molecules also interact through the NCS groups when adsorbed at the TiO2 surface. Comparing the N719 and the N3 molecule, the fraction of NCS groups interacting through the sulfur atoms is smaller for N719 than for N3. We also note that the counterion TBA+ is coadsorbed with the N719 and BD molecules although the amount was smaller than expected from the molecular formulas. Comparing the valence levels for the dyes adsorbed on TiO2, the position of the highest occupied electronic energy level is similar for N3 and N719, while that for BD is lower by 0.25 eV relative to that of the other complexes.
光电子能谱（PES）的元素特异性已被用于比较从溶液吸附到纳米结构TiO₂上的染料Ru(tcterpy)(NCS)₃（BD）和Ru(dcbpy)₂(NCS)₂的电子结构和分子结构。研究了Ru(dcbpy)₂(NCS)₂的酸性形式（N3）及其以四丁基铵（TBA⁺）作为抗衡离子的二倍去质子化形式（N719）。染料的O1s光谱比较表明，这些染料通过羧基与TiO₂表面的相互作用非常相似。然而，我们观察到一些染料分子在吸附于TiO₂表面时也通过NCS基团相互作用。比较N719和N3分子，通过硫原子相互作用的NCS基团的比例对于N719来说比N3小。我们还注意到，抗衡离子TBA⁺与N719和BD分子共吸附，尽管其数量比分子式预期的要少。比较吸附在TiO₂上的染料的价态能级，N3和N719的最高占据电子能级位置相似，而BD的最高占据电子能级相对于其他配合物低0.25 eV。
