| Research Abstract |
In this project, intracluster electron transfer from an alkali atom to constituent molecules and the following chemical reactions have been investigated by photoionization mass spectroscopy, negativeion photoelectron spectroscopy, photodissociation of cluster ions, and also by quantum chemical calculations. In the photoionization study, size-dependent stability of clusters is examined for the systems consisting of an alkali atom M (M=Li, Na, and K) and acrylonitrile (AN; CH2=CHCN) molecules These clusters are considered as microscopic models of initial systems for anionic polymerization reaction in the bulk solution. In the photoionization mass spectra of M(AN)_n^+, strong ion signals were observed commonly at n=3. This magic number can be explained by the electron transfer from the metal atom to vinyl molecules followed by intracluster anionic oligomerization to produce stable species with substituted cyclohexane ring structures. These clusters with n=3 were also found to be extraordi
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nary stable from the photodissociation experiments prior to photoionization. Quantum chemical calculation for Na(AN) based on density functional theory also supports the intracluster electron transfer from the metal atom to molecules.
Along with the neutral systems noted above, intracluster reactions in the negative ions of the NaAN clusters have also been examined by mass-selected photoelectron spectroscopy. In this experiment, we obtained photoelectron spectra of cluster negative ions, which were produced by laser vaporization and mass selected in a TOF mass spectrometer, by using a magnetic-bottle TOF electron energy analyzer. The obtained photoelectron spectrum of Na(AN)_3- were found to have the similar band structure with that of (AN)_3- and also with that of the 1,3,5-cyclohexanetricarbonitrile molecular negative ion obtained by Kondow and his coworkers. This observation indicates that the excess electron in Na(AN)_3- promotes the intracluster anionic oligomerization and that the cyclic oligomer is produced as discussed for the neutral M-vinyl molecules systems. Less
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