| Abstract
| - The adsorption state and thermal stability of V(benzene)2 sandwich clusters soft-landed onto a self-assembledmonolayer of different chain-length n-alkanethiols (Cn-SAM, n = 8, 12, 16, 18, and 22) were studied bymeans of infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD).The IRAS measurement confirmed that V(benzene)2 clusters are molecularly adsorbed and maintain a sandwichstructure on all of the SAM substrates. In addition, the clusters supported on the SAM substrates are orientedwith their molecular axes tilted 70−80° off the surface normal. An Arrhenius analysis of the TPD spectrareveals that the activation energy for the desorption of the supported clusters increases linearly with the chainlength of the SAMs. For the longest chain C22-SAM, the activation energy reaches ∼150 kJ/mol, and thethermal desorption of the supported clusters can be considerably suppressed near room temperature. Theclear chain-length-dependent thermal stability of the supported clusters observed here can be explained wellin terms of the cluster penetration into the SAM matrixes.
|
