AFM is increasingly used in biological sciences not only for imaging but also for measuring the force of interaction between bio-molecular pairs. To conduct the force measurement on various biomolecular pairs effectively, we propose a new experimental system using the complex that is composed of a ligands-functionalized polymer and its receptors. This system is expected to prevent deactivation of bio-molecules, as well as non-specific adsorption between a cantilever tip and a substrate surface, since the bio-molecules of interest are bound on the flexible polymer. In an initial trial, we applied it to measure the force of interaction between avidin and biotin using CM-cellulose as a base polymer. As a result, we got 60−160 pN interaction forces which are proportional to logarithm of force loading rate, which is consistent with the reported trends.
The infrared (IR) chemiluminescence spectra of CO2 molecules were measured during the steady-state CO oxidation over Pt(110) and Pt(111) surfaces. Analysis of the IR emission spectra indicates that the bending vibrational temperature (TVB), as well as the antisymmetric vibrational temperature (TVAS), was higher on Pt(110) than on Pt(111). On the Pt(110) surface, the highly excited bending vibrational mode compared to the antisymmetric vibrational mode was observed under reaction conditions at low CO coverage (θCO<0.2) or at high surface temperatures (TS≥700 K). This can be related to the activated complex of CO2 formation in a more bent form on the declined (111) terraces of the Pt(110)(1×2) structure. On the other hand, at high CO coverage (θCO≥0.2) or at low surface temperatures (TS<650 K), TVAS was higher than TVB, which can be caused by the reconstruction of the Pt(110)(1×2) surface to the (1×1) form with high CO coverage.
Initial adsorption dynamics of O2 on Si(111)-7×7surface at room temperature was investigated by a supersonic molecular beam technique in conjunction with real-time X-ray photoelectron spectroscopy using synchrotron radiation. The initial sticking probability and the saturation coverage as a function of the translational kinetic energy of impinging O2 were measured in the wide range from 0.03 eV, namely thermal gas generated by back-filling condition, to 2.3eV. We proposed a trapping-mediated process as a dominant adsorption mechanism at low kinetic energy region, while at high kinetic energies approximately over 0.06eV the direct adsorption overlapping the trapping-mediated one whose contribution became small with increasing incident energies were expected to be a dominant adsorption mechanism. A gradual increase of the saturation coverage with increasing kinetic energy was clearly observed in the incident energy of 0.4eV to 1.7eV where the direct adsorption took over. The peak area intensity over 1.7eV regions is approximately 1.8 times larger than that for 0.03eV. These results indicate that the incident energy essentially induces the activated adsorption corresponding to the enhancement of the further O2 dissociative adsorption even at room temperature.
A novel structure of water aggregate is revealed by means ofscanning tunneling microscopy (STM). We find that water molecules are self-assembled into one-dimensional chains at 78 K on Cu(110). Reflecting the two-fold symmetry of the surface, the chain grows exclusively along the direction perpendicular to the Cu rows. The chain exhibits a zigzag structure in the STM images with a period of 7.2 Å, and grows to a length of ∼1,000 Å. This is incontrast to the two-dimensional water overlayer on close-packed metallic surfaces of three-fold symmetry. We propose that water hexamers mainly constitute the zigzag 1D chain. Two-dimensional overlayer appears only at high coverage.
In order to discuss quantitatively the effect of functional groups of activated carbon fibers (ACFs) on the electric double-layer characteristics, ACFs with various amounts of functional groups were prepared from the same ACFs by redox methods. The amounts of functional groups of ACF were determined and compared using two different methods of back titration and X-ray photoelectron spectroscopy (XPS). In the case of the aqueous electrolyte, the electric capacity depended more on oxygen functional groups than on BET surface area. At the greatest 30% increase in electric capacity was obtained by using ACFs with different amounts of oxygen functional groups between the positive and negative electrodes. It was considered that a larger number of functional groups promote not only the wettability of electrodes but also the negative charge of electrodes leading to an increase in capacity. On the other hand, in the case of the organic electrolyte, the pore structure seemed to be a more dominant factor than functional groups. Also, the characteristics of the electrodes after 30,000-cycle charge-discharge were determined to confirm the reliability in an extended cycle operation.
In order to establish the charge migration mechanism, we examined the electronic structure of bases in DNA strands by means of resonant photoemission spectroscopy near the Fermi level. Because the N atoms are only included in bases in DNA strands, the electronic orbital features of the bases can be specified selectively at the resonant excitation from the N core level to unoccupied states. On the obtained resonant photoemission spectra for both poly(dG) · poly(dC) and poly(dA) · poly(dT) DNAs, we observed a kinetic energy shift of N-KLL Auger electrons and an intensity enhancement of valence electrons. These results clearly show the localized unoccupied electronic states of the bases. Therefore, it is concluded that the charge hopping model is pertinent for the charge migration mechanism in DNA strands, when electrons pass through the unoccupied states.
Angle-resolved ultra-violet photoelectron spectroscopy (ARUPS) has been studied using a multiple scattering theory. ARUPS spectra of adsorbed large molecules on surface have information of geometric and electronic structures for near neighbors of an excited molecule. In order to obtain useful information, analyses of scattering order are discussed in terms of real-space multiple scattering theory. The theory allows us to discuss geometric and electronic structures of the excited molecule and local structure of near-neighbor molecules. In this paper, we have studied ARUPS of copper phthalocyanine. The single-scattering calculations are enough to estimate main structures of the spectra. However, the single scattering results are not converged to infinite order multiple scattering results. Our scattering order analysis shows double-scattering processes are important to approximate the infinite-order multiple scattering results. Moreover, we also find that the results of double scattering processes including intermolecular scattering path improve the data of single scattering. If we want to discuss fine structures of ARUPS, we should consider higher order multiple scattering processes.
The mechanisms of beautifulness of Japanese black and brown hairs, the structure factors influencing on appearance, and technologies to develop hair shine and vividness of color are reviewed. Various types of pores in each part of the fiber generated by hair damage cause light scattering, which leads to loosing hair shine. Pore fixation technology using aqueous malic acid solution was found effective to reduce light scattering due to swelling ability of the organic acid. Furthermore, the novel chroma enhancement technology with using only shampoo and conditioner is reviewed. Fibers with surface structures having fine concaves and convexes show developing vividness in color. The mechanism of the color enhancement was explained by approximation theory of effective media, by which the refractive index of the treated fiber surfaces was estimated to be less than 1.3.