Hironori Tsunoyama

Photoionization and density functional study of clusters of alkali metal atoms solvated with acetonitrile molecules, M(CH3CN)n (M=Li and Na)

Abstract Photoionization mass spectroscopy of clusters of alkali metal atoms solvated with acetonitrile molecules, M(CH 3 CN) n (M=Li and Na), has shown that their ionization potentials decrease from n =1 to 3, while they increase for n ⩾4. Calculations based on density functional theory are also made for these clusters and their cations with n =1–3. The nature of the anomalous n dependence of the ionization potential is discussed in relation to the stabilization of neutral clusters due to dipole–dipole interaction between acetonitrile molecules.

Photoionization and density functional theory study of clusters of acetone containing an alkali metal atom, M((CH3)2CO)n (M=Li, Na): Intracluster electron transfer from metal to acetone in 1:1 complexes

Abstract Ionization threshold energies of clusters of Li and Na atoms solvated by acetone have been determined by laser photoionization. The thresholds for 1:1 complexes agree well with calculated adiabatic ionization potentials based on density functional theory. The structures and charge distributions obtained from the calculation show that electron transfer from the alkali atom to acetone occurs more efficiently in Li((CH3)2CO) than in Na((CH3)2CO). This difference in the extent of electron transfer can be understood by a consideration of the orbital overlap between the metal np and O2p orbitals and the sp hybridization on the alkali atom.

Photodissociation of Mg(CH2=CHCN)n+: Excited electronic states of n=1 and 2 and intracluster electron transfer for n=3 and 4

Photodissociation spectra of mass-selected Mg(CH2=CHCN)n+ cluster ions were investigated in the wavelength region from 415 to 225 nm and 495 to 225 nm for n=1 and 2, respectively, by monitoring the total yield of fragment ions. The absorption bands exhibit large shifts from the 2P–2S resonance line of Mg+. In the spectrum of n=1, there are two bands at 26u200a400 and 40u200a800u2009cm−1. On the other hand, three absorption bands at 22u200a600, 28u200a800, and 37u200a500u2009cm−1 appear in the spectrum of n=2. The most stable structures in the ground state for n=1 and 2 were obtained by DFT(B3LYP/6-31+G*) calculations, and transition energies from these structures were obtained by using configuration interaction singles approach with the same basis set. The calculated excitation energies show good agreement with the experimental results. In addition, fragment ions of Mg(CH2=CHCN)m+ with m=4 and 5 are found to have high intensities from the parent ions of n=6–10 at a dissociation wavelength of 355 nm. From the result of theoretical ca...

Photoionization mass spectroscopy of clusters of alkali metal atoms with methyl vinyl ketone and acrolein: intracluster oligomerization initiated by electron transfer from a metal atom

Abstract We have investigated the photoionization mass spectrometry of clusters of an alkali metal atom (M: Na and K) and methyl vinyl ketone (MVK) or acrolein (AC) to discuss the intracluster oligomerization. In the mass spectra of M(MVK) n , strong ion signals at n =3 are observed. This magic number is explained by the cyclohexane derivative formation in the intracluster oligomerization of MVK initiated by electron transfer from an alkali metal atom. The results of the calculation for Na(MVK) based on density functional theory also show the presence of intracluster electron transfer. On the other hand, in M(AC) n , intensity enhancement is observed at n =4. These intensity enhancements may be due to intracluster reaction in M(AC) n , which is different from the case of M(MVK) n .

Size-dependent structures of NanIn−1+ cluster ions with a methanol adsorbate: A combined study by photodissociation spectroscopy and density-functional theory calculation

Methanol adsorption sites on NanI+n-1 ions were investigated. Photoexcitation to charge-transfer states of NanI+n-1 (methanol) predominantly produces two fragment ions: Nan-1I+n-2 (methanol) (neutral NaI loss) and Nan-1I+n-2(neutral NaI and methanol loss), without forming NanI+n-1 (methanol loss). The relative intensities of these fragments are correlated with the geometries and binding energies.

ADSORPTION REACTION OF POLAR ORGANIC MOLECULES ON

We have examined chemical reactions of small silicon cluster ions for n = 7 - 16 with polar organic molecules M (M = CH3CN, CD3OD, C2H5CN, and C2H5OH). The intensities of the adsorption products for m = 1 and 2 were investigated as a function of n. We found for all polar molecules that the relative intensity of SinM+ to the unreacted is smaller for n = 11, 13, and 14, that is, the adsorption reactivity is smaller for these n than others. It was also commonly observed that the ion are more intense than neighboring n. We discussed the relationship of the reactivity with the geometrical structures and the stabilities of the bare ions and adsorbed ions, from theoretical calculations based on density functional theory.