We have examined the infrared (IR) spectra of electron-beam (EB) irradiated C60 films, using in situ IR spectroscopy in the temperature range of 60–300 K. The irradiation-time evolution of the IR spectra shows that two highly intense new peaks finally appear around 565 and 1340 cm−1 when the EB-induced C60 polymerization was saturated. To determine the cross-linked structure of the polymer explicitly, we have compared the IR spectra with theoretical spectra obtained from the cross-linked structure of all C120 stable isomers derived from the general Stone–Wales (GSW) rearrangement, using first-principles density-functional calculations. Since each C120 isomer has the same cross-linked structure as that of its corresponding one-dimensional (1D) C60 polymer, the IR modes obtained from the cross-linked structure of C120 are close to those obtained from the corresponding 1D polymer. Comparison between the experimental and theoretical IR spectra suggests that the 1D peanut-shaped C60 polymer has a cross-linked structure roughly similar to that of the P08 peanut-shaped C120 isomer.

Wings of insects exhibit many functions apart from flying. In particular, their antireflection function is important for insects to avoid detection by their enemies. This function can be applied to antireflection biomimetic films in engineering fields. For such applications, confirming the antireflection mechanisms of insect wings is important. Herein, we used electron microscopy to compare the surfaces of green lacewing wings with and without a surface wax structure and recorded the transmittance spectra to clarify the surface structural and optical properties of insect wings. The spectral transmittance was higher for wings with a surface wax structure than for wings without a wax layer in the light wavelength regime from 500 to 750 nm. We constructed a concise model of the green lacewing wing with flake-like surface structure with a graded effective refractive index corresponding to the wing samples with a surface wax layer; we also constructed a simple thin-film model corresponding to the wing samples without a wax layer. The graded refractive indices were calculated using the effective medium theory, and the transmittance spectra of such models were then calculated using the transfer-matrix method. It was observed that the calculated spectra are in good agreement with the experimental results. In addition, wing samples without a surface structure induce thin-film interference. These results suggest that a wax structure can reduce the reflectance and increase the transmittance enabling the green lacewings to avoid detection by their enemies. These findings may lead to further advances in both the biomimetic field and fundamental research fields.

A 3 kV electron-beam irradiation of a C60 film gives rise to formation of one-dimensional (1D) uneven peanut-shaped C60 polymer with a cross-linked structure close to that of the P08 C120 stable isomer obtained from the general Stone–Wales rearrangement. In this study, we examined the evolution of infrared (IR) spectra of C60 films with respect to electron beam (EB) irradiation time, using in situ high-resolution IR spectroscopy and first-principles density-functional calculations, and found semi-quantitatively that the 1D uneven peanut-shaped C60 polymer is formed via intermediate polymers with a cross-linkage close to that of P04 and P06 C120 isomers obtained from GWS rearrangement. In addition, we examined the dependence of EB-induced C60 polymerization on an incident energy of EB in the range 3–7 kV. IR spectra obtained for 5 and 7 kV EB irradiation of C60films showed the same product as for 3 kV EB irradiation. However, when 5 and 7 kV EBs continued to irradiate C60 films for a long time after the polymer formation, the 1D peanut-shaped polymer did not proceed to become 1D polymers with a more coalesced linkage than that of the P08 one but was destroyed to become amorphous carbons.

The infrared (IR) phonon properties of one-dimensional (1D) metallic peanut-shaped C60 polymers, which exhibit an energy gap below 60 K [Y. Toda et al., Appl. Phys. Lett. 92, 094102 (2008)] that is similar to the Peierls transition of quasi-1D metallic materials, have been examined in the temperature range of 30–300 K by high-resolution in-situ IR spectroscopy. We observed an IR phonon anomaly in which two new IR modes appear at 50 K and become increasingly anomalous with decreasing temperature in a similar manner as phase phonons associated with charge density waves in quasi-1D condensates.

We studied the formation and healing of adatom defects on a Si(111)7ϫ7 surface bombarded by 0.5-keV Ar ions. Scanning tunneling microscopy showed that adatoms were missing from the Si(111)7ϫ7 surface. Increasing the temperature during the bombardment increased the percentage of missing adatom sites. However, the percentage saturated at 400 K, then decreased with temperature. This temperature dependence was due to competition between the formation and healing of adatom defects; defect formation dominated at low temperatures, but was overcome by healing at high temperatures. We analyzed the temperature dependence using a rate equation for missing adatoms which included the temperature-independent sputtering and other temperature-dependent formation and healing processes. Activation energies of 0.29 and 0.39 eV were obtained for the temperature-dependent formation and the healing of adatom defects. The temperature-dependent formation was attributed to vacancy-adatom recombination, and the temperature-dependent healing was attributed to the interstitial atom-missing adatom site recombination. These vacancy and interstitial atoms were generated in the collision cascade under the surface. Some of them migrated to the surface and contributed to the temperature-dependent formation and healing of missing adatoms.