Masashi Hashimoto

Production of hyperlithiated Li2F by a laser ablation of LiF–Li3N mixture

Abstract Lithium-excess binary clusters Li n F n −1 ( n =2–9) were detected by photoionization time-of-flight mass spectrometry in a supersonic cluster beam generated by a laser ablation of a solid mixture of lithium fluoride and nitride. Laser power dependence of the Li 2 F + signal intensity has indicated that the ionization energy of the hyperlithiated Li 2 F molecule is lower than 4.66 eV. The theoretical vertical ionization energy obtained by the CCSD(T)/6-311+G(d)//B3LYP/6-311+G(d) calculations are 4.47 eV. No nitrogen-containing clusters were detected. The absence of Li 4 N is ascribed to the exothermicity of the reaction, 2Li 3 N→N 2 +Li 6 .

Thermodynamic stability and optimized structures of hypervalent molecules M2CN (M = Li, Na, K)

Abstract The hypervalent M2CN (M = Li, Na, K) molecules have been detected in the vapor at elevated temperatures over mixtures of alkali metals and sodium cyanide by means of Knudsen-effusion mass spectrometry. The experimentally obtained ionization energies were IP (Li2CN+) = 5.4 ± 0.2 eV, IP(Na2CN+) = 4.9 ± 0.2 eV and IP (K2CN+) = 4.0 ± 0.2 eV, agreeing well with the theoretical values 5.13, 4.66 and 3.7 eV, respectively, calculated for the vertical ionization. The energies of dissociation into MCN and M were D°0 (LiNCue5f8Li) = 137 ± 14 kJ/mol, D°0 (NaCNue5f8Na) = 104 ± 14 kJ/mol, and D°0 (KCNue5f8K) = 81 ± 8 kJ/mol. Although the theoretically calculated values were slightly lower (103.8 kJ/mol for Li2CN, 72.8 kJ/mol for Na2CN, and 74.5 kJ/mol for K2CN), the dissociation energies indicate moderately strong bonding of alkali metals to the alkali cyanides (MCN) of octet molecules. The agreement between experiment and theory confirms the existence of the M2CN species, which are the hypervalent molecules with more than one electronegative atom. The theoretically optimized structures of M2CN are quite similar to each other, with four isomers (two planar structures with Cs symmetry and two linear structure with C∞v symmetry), although there are differences in bond length. The favored structure of M2CN has Cs symmetry and is best described as a complex of the CN− anion with the M+2 cation.

Practical Method for Producing a Large Amount of Isotopically Enriched Silicon by Infrared Multi-Photon Dissociation of Hexafluorodisilane

This paper presents a practical method for producing highly enriched silicon isotopes utilizing laser irradiation. One- or two-frequency CO2 laser irradiation has been employed to separate the desired isotope of silicon by means of infrared multi-photon dissociation (IRMPD) of hexafluorodisilane (Si2F6) molecules using a flow reaction system. The production of Si2F6 with a 28Si fraction of 99.1% at a rate of 0.67 g (28Si)/h was successfully accomplished with a yield of about 63% by two-frequency laser irradiation. Enriched SiF4 gas with 30Si exceeding 31% was also continuously obtained at a production rate of 0.12 g/h by one-frequency laser irradiation.

Programmable Optical Parallel Processor By Polarization Encoding: Cascade Operation

Optical parallel processor which performs cascade logic operations is newly constructed. The encoding concept using polarization state of light and the separation of the encoded light together are the key to the programmability for any logic operation. The operation kernel determines the logic operation to be executed only by spatially filtering spatially the encoded light. Real-time programmable cascade logic operations for three binary patterns have been demonstrated experimentally with the optical processor using a liquid-crystal spatial light modulator as the operation kernel. Up to five-step cascede operation is anticipated by using microchannel spatial light modulator having photomultifying capability as the polarization encoder.

Neighborhood operations of optical parallel processor

An optical parallel processor based upon polarization encoding that performs neighborhood operations is implemented by newly introducing an optical shifter. The experimental results of edge extraction are demonstrated.