Interaction of highly charged ions with carbon-based materials using Kobe EBIS

Interaction of highly charged ions (HCIs) with surfaces produce various specific phenomena as a consequence of the potential energy that HCI possesses. In the present study, we have observed photon emission, structural, magnetic, and electronic modification on various carbon-based materials such as carbon nanotube by the impact of HCIs using an electron beam ion source named Kobe EBIS installed at the Kobe University. In order to study the potential effect, HCIs of Ar^q+ (q = 6–16) with the intensity of 0.1–1 nA are projected on the surface with a constant kinetic energy (16 keV). For photon emission measurements, we observed spatial and spectral distribution of visible light emission from the surface during irradiation with HCIs. On the other hand, the structural modification of multi-walled carbon nanotubes (MWCNTs) irradiated with HCIs has been analyzed using a transmission electron microscopy and Raman spectroscopy. Irradiation effects on the resistivity of single MWCNT supported on micrometer scale bridge pattern were also measured. We have also measured magnetic structure of highly oriented pyrolytic graphite irradiated with HCIs using electron spin resonance at low temperature. At the present paper, we will review our recent experimental results on the interaction of HCI with various carbon-based materials.     

A CO Adsorption Site Change Induced by Copper Substitution in a Ruthenium Catalyst for Enhanced CO Oxidation Activity

Ru is an important catalyst in many types of reactions. Specifically, Ru is well known as the best monometallic catalyst for oxidation of carbon monoxide (CO) and has been practically used in residential fuel cell systems. However, Ru is a minor metal, and the supply risk often causes violent fluctuations in the price of Ru. Performance‐improved and cost‐reduced solid‐solution alloy nanoparticles of the Cu‐Ru system for CO oxidation are now presented. Over the whole composition range, all of the Cu_xRu_1?x nanoparticles exhibit significantly enhanced CO oxidation activities, even at 70 at % of inexpensive Cu, compared to Ru nanoparticles. Only 5 at % replacement of Ru with Cu provided much better CO oxidation activity, and the maximum activity was achieved by 20 at % replacement of Ru by Cu. The origin of the high catalytic performance was found as CO site change by Cu substitution, which was investigated using in situ Fourier transform infrared spectra and theoretical calculations.     

Coloring–decoloring behavior of fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid oligomer/acetone composite in methanol

A reddish‐brown fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) oligomer/acetone composite was prepared by heating the white oligomer powder with acetone at 80 °C for 3 h. The color was not observed in the corresponding non‐fluorinated AMPS oligomer/acetone composite, which was prepared under similar conditions. The coloring was probably caused by the formation of acetone polyaldol condensation products in the fluorinated oligomeric gel network cores. The colored R_F‐(AMPS)_n‐R_F/acetone composite powders were stable and did not exhibit any color change after 2 years in natural light at room temperature. The colored composite powders dissolved in methanol to give a reddish‐brown solution at room temperature. However, the retro‐polyaldol condensation decolored the solution after 1 day at room temperature. This is the first example of the retro‐aldol polycondensation of acetone under mild conditions. The decoloration increased by between 38‐ and 70‐fold under UV irradiation, compared with that in dark conditions. The coloring–decoloring behavior was consistent and repeatable; therefore our fluorinated oligomer/acetone composites are promising candidates for new fluorinated coloring materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2555–2564     

Mössbauer study of new vanadate glass with large charge-discharge capacity

Charge-discharge capacity and cyclicity of lithium ion battery (LIB) was evaluated in which 15Li₂O·10Fe₂O₃·xSnO₂·5P₂O₅·(70–x)V₂O₅ glass (x?=?0 and 20 in mol%, abbreviated as xLFSPV) was used as a cathode. A local structure of xLFSPV glass before and after charging was investigated by ⁵⁷Fe- and ¹¹⁹Sn-Mössbauer spectroscopies. ⁵⁷Fe-Mössbauer spectrum of xLFSPV glass with ‘x’ of 20 was composed of a doublet with isomer shift (δ) of 0.35_±0.02 mm s^???1 and quadrupole splitting (Δ) of 0.88_±0.03 mm s^???1 due to distorted Fe^IIIO₄ tetrahedra. ¹¹⁹Sn-Mössbauer spectrum of this glass consisted of a doublet with δ of 0.08_±0.01 and Δ of 0.52_±0.01 mms^???1 due to distorted Sn^VIO₆ octahedra. After discharging the battery from 4.5 to 1.0 V, larger δ of 0.40_±0.03 mm s^???1 and Δ of 0.94_±0.04 mm s^???1 were obtained, indicating that both iconicity of Fe-O bonds and local distortion of Fe^IIIO₄ tetrahedra were increased. On the contrary, identical δ of 0.09_±0.01 mm s^???1 and Δ of 0.50_±0.01 mm s^???1 were observed in the ¹¹⁹Sn-Mössbauer spectrum of 20LFSPV glass after the discharge, indicating that chemical environment of Sn^IVO₆ octahedra was not affected after the discharge. Charge-discharge curve of LIB containing 20LFSPV glass as a cathode active material recorded under the current density of 8.3 mA g^???1 (0.011 mA cm^???2) between 1.0 and 4.5 V showed a large initial charge capacity of 431.1 mAh g^???1 and discharge capacity of 382.3 mAh g^???1, respectively. These results indicate that 20LFSPV glass could be a new cathode active material for LIB.     

Rational Design for Rotaxane Synthesis through Intramolecular Slippage: Control of Activation Energy by Rigid Axle Length

We describe a new concept for rotaxane synthesis through intramolecular slippage using π‐conjugated molecules as rigid axles linked with organic soluble and flexible permethylated α‐cyclodextrins (PM α‐CDs) as macrocycles. Through hydrophilic–hydrophobic interactions and flipping of PM α‐CDs, successful quantitative conversion into rotaxanes was achieved without covalent bond formation. The rotaxanes had high activation barrier for their de‐threading, so that they were kinetically isolated and derivatized even under conditions unfavorable for maintaining the rotaxane structures. ¹H NMR spectroscopy experiments clearly revealed that the restricted motion of the linked macrocycle with the rigid axle made it possible to control the kinetic stability by adjusting the length of the rigid axle in the precursor structure rather than the steric bulkiness of the stopper unit.     

Evaluation of measurement uncertainty in the elemental analysis of sintered silicon carbide using laser ablation in liquid—inductively coupled plasma mass spectrometry with external calibration and isotope dilution

Accreditation and Quality Assurance - The goal of this study was to evaluate the uncertainty of elemental analytical methods that use laser ablation in liquid (LAL) as a pretreatment. After LAL...