Synthesis of monodispersed model catalysts using softlanding cluster deposition

In nanocatalysis, clusters deposited on solid, well-defined surfaces play an important role. For the detection of size effects it is, however, important to prepare samples consisting of deposited clusters of a single size, as their chemical properties change with the exact number of atoms in the cluster. In this paper, the experimental tools are presented to prepare such model systems. The existence of monodispersed clusters is confirmed by various experimental findings. First, the carbonyl formation of deposited Nin clusters shows no change in the nuclearity when comparing the size of the deposited clusters with one of the formed carbonyls. Second, scanning tunneling microscopy (STM) studies show that fragmentation of Sin clusters upon deposition can be excluded. In addition, the adsorption behavior of CO on deposited Pd atoms points to the existence of single atoms on the surface. Furthermore, CO oxidation results on Aun clusters confirm the existence of monodispersed clusters trapped on well-defined adsorption sites. Finally, we use Monte-Carlo simulations to define the range of clusters and defect densities, for which monodispersed clusters can be expecte

Cu+(H2O)n の赤外スペクトルと溶媒和構造

2005年分子構造総合討論会, 2005年9月27日-30日, タワーホール船堀(東京), 1P03

赤外光解離分光による[Al(NH3)n]+の溶媒和構造に関する研究

2005年分子構造総合討論会, 2005年9月27日-30日, タワーホール船堀(東京), 3P03

Low-Temperature Production of Genuinely Amorphous Carbon from Highly Reactive Nanoacetylide Precursors

Copper acetylide is a well-known explosive compound. However, when the size of it crystals is reduced to the nanoscale, its explosive nature is lost, owing to a much lower thermal conductance that inhibits explosive chain reactions. This less explosive character can be exploited for the production of new carbon materials. Generally, amorphous carbon is prepared by carbonization of organic compounds exposed to high temperature, which can induce partial crystallization in graphite. In this work, we present a new method in which the carbonization reaction can proceed at a lower annealing temperature (under 150°C) owing to the highly reactive nature of copper acetylide, thus avoiding crystallization processes and enabling the production of genuinely amorphous carbon materials

Infrared photodissociation spectra and solvation structures of Cu+(H2O)n (n = 1-4)

Coordination and solvation structures of the Cu+(H2O)n ions with n = 1–4 are studied by infrared photodissociation spectroscopy and density functional theory calculations. Hydrogen bonding between H2O molecules is detected in Cu+(H2O)3 and Cu+(H2O)4 through a characteristic change in the position and intensity of OH-stretching transitions. The third and fourth waters prefer hydrogen-bonding sites in the second solvation shell rather than direct coordination to Cu+. The infrared spectroscopy verifies that the gas-phase coordination number of Cu+ in Cu+(H2O)n is two and the resulting linearly coordinated structure acts as the core of further solvation processes.This is a postprint of an article published by Elsevier B.V. in Chemical Physics Letters, 2006, available online: http://doi.org/10.1016/j.cplett.2006.06.036This work was supported in part by “Nanotechnology Support Project” and Grant-in-Aid for Scientific Research (No. 17550014) of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan

Infrared Photodissociation Spectroscopy of Al+(CH3OH)n (n=1-4)

Infrared photodissociation spectra of Al+(CH3OH)n (n=1-4) and Al+(CH3OH)n-Ar (n=1-3) were measured in the OH stretching vibration region, 3000-3800 cm-1. For n=1 and 2, sharp absorption bands were observed in the free OH stretching region, all of which were well reproduced by the spectra calculated for the solvated type geometry with no hydrogen bond. On the other hand, for n=3 and 4, there were broad vibrational bands in the energy region of hydrogen bonded OH stretching vibrations, 3000-3500 cm-1. Energies of possible isomers for the Al+(CH3OH)3,4 ions with hydrogen bonds were calculated in order to assign these bands. It is found that the third and fourth methanol molecules form hydrogen bonds with methanol molecules in the first solvation shell, rather than a direct bonding with the Al+ ion. We obtained no evidence of the insertion reaction for the present Al+(CH3OH)n system, which was reported in Al+(H2O)n previously. One possible explanation of the difference between these two systems is that the potential energy barriers between the solvated and inserted isomers in the Al+(CH3OH)n system is too high to form the inserted type isomers.This is a preprint of an article published by American Chemical Society in Journal of Physical Chemistry A, 2007, available online: http://pubs.acs.org/doi/abs/10.1021/jp067622c.This work was supported by the Joint Studies Program (2004) of the Institute for Molecular Science. A part of this work was also supported by "Nanotechnology Support Project" and Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan