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排序方式: 共有252条查询结果,搜索用时 30 毫秒
1.
Okuno Y Yokoyama T Yokoyama S Kamikado T Mashiko S 《Journal of the American Chemical Society》2002,124(24):7218-7225
We made theoretical calculations for a benzonitrile molecule and its clusters in the gas phase and as adsorbed on the Au(111) surface, to explain the observation by scanning tunneling microscope, that is, the trimer formation of cyanophenyl porphyrins adsorbed onto the Au(111) surface. With regard to the gas-phase species, ab initio calculations showed that (1) the benzonitrile dimer has a single stable structure that is planar and antiparallel; (2) the trimer has two isoenergetic stable structures, that is, a planar and cyclic structure and an antiparallel and nonplanar one; (3) the clusters are more stable, at low temperatures, than the monomer. For the adsorbed species, we made quantum mechanical/molecular mechanical calculations in which the interaction between the adsorbates and the surface is evaluated in a molecular-mechanical way by using analytical potential functions and an image charge model. Because the stable structures were found to be similar to those in the gas phase, the cluster formation of adsorbed cyanophenyl porphyrins was attributed to the interaction between cyanophenyl groups, which is barely affected by adsorbate-surface interaction. It was also found that the adsorbed cyclic benzonitrile trimer is more stable than the monomer and the dimer because the relative stability is dependent on enthalpy alone. We therefore concluded that the preferential formation of trimers by the adsorbed cyanophenyl porphyrins is due to the negligible contribution of entropy to the relative stability of the adsorbed species and that the adsorption hardly changes the situation found in the gas phase. 相似文献
2.
The number of helicopter operations has rapidly increased during the last 20 years in Japan. Helicopter noise sounds different from other aircraft; the waveform of the sound pressure is impulsive and the signal duration is relatively long. The Environmental Agency of Japan implemented new guidelines for evaluating noise exposure around small airports, including heliports, in 1990. This study was executed in connection with the development of provisional guidelines. Psychoacoustic experiments were carried out to identify an evaluation index for helicopter noise. In order to examine the effect of duration independently, we not only used original sound recordings, but also synthesized sound signals. The durations of these sound signals were time compressed or expanded without degrading the quality of the original sound recording. The test results show that the effect of duration is significant, and that the A-weighted sound exposure level is a better index than the maximum A-weighted sound pressure level for the evaluation of helicopter noise. 相似文献
3.
Tetsuo Tsuchiya Akio Watanabe Tomohiko Nakajima Toshiya Kumagai 《Applied Physics A: Materials Science & Processing》2010,101(4):681-684
Europium-doped yttrium oxide (Y2O3:Eu) thin films were successfully deposited on quartz and ITO/glass substrates by excimer-laser-assisted metal organic deposition
(ELAMOD) at low temperatures. The effects of laser wavelength and thermal temperature on the films’ crystallinity and photoluminescence
properties were investigated. Films irradiated by an ArF laser at 80 mJ/cm2 and 400–500°C were highly crystallized compared with those prepared by thermal MOD. In contrast, when the film was irradiated
by a KrF laser at 500°C, no crystalline Y2O3:Eu was formed. The Y2O3:Eu film irradiated by the ArF laser at 80 mJ/cm2 and 500°C showed typical PL spectra of Eu3+ ions with cubic symmetry and a 5D0→7F2 transition at ∼612 nm. The PL intensity at 612 nm was much higher for the film prepared with ELAMOD than for that prepared
by the thermal-assisted process, and the photoemission intensity of the film prepared with ELAMOD strongly depended on the
substrate material. 相似文献
4.
Karataev P Araki S Hamatsu R Hayano H Muto T Naumenko G Potylitsyn A Terunuma N Urakawa J 《Physical review letters》2004,93(24):244802
An experiment on the investigation of optical diffraction radiation (ODR) from a slit target as a possible tool for noninvasive electron beam-size diagnostics has been performed at the KEK accelerator test facility. The experimental setup has been installed at the diagnostics section of the extraction line. We have performed the first incoherent ODR observation from a slit target. The measured angular distributions are in reasonable agreement with the theoretical expectation. The beam-size effect onto the ODR angular pattern has been observed. Moreover, the sensitivity to the beam size as small as 14 microm has been achieved. 相似文献
5.
This paper presents a method of measuring a light field of a light source with high directional resolution using a mirrored
ball and a pinhole camera. The light field describes a spatial and directional distribution of radiances from the light source.
The directional distribution is expanded by a reflection on the mirrored ball, and the radiances are measured by a charge-coupled
device (CCD) camera with a pinhole lens. The light source is laterally moved by a robot arm to measure the directionally expanded
light field, and each pixel on a CCD can obtain the radiances from the light source through the pinhole lens with high directional
resolution. The light field is estimated from the pixel value and the position of each pixel using a ray tracing technique.
The light field of a krypton lamp was experimentally measured by the proposed method, and the accuracy of the measurement
was evaluated against the irradiances measured by a spectro-radiometer at sample points. 相似文献
6.
7.
Norimichi Tsumura Daisuke Kawazoe Toshiya Nakaguchi Nobutoshi Ojima Yoichi Miyake 《Optical Review》2008,15(6):292-294
A simple regression-based model of skin diffuse reflectance is developed based on reflectance samples calculated by Monte
Carlo simulation of light transport in a two-layered skin model. This reflectance model includes the values of spectral reflectance
in the visible spectra for Japanese women. The modified Lambert Beer law holds in the proposed model with a modified mean
free path length in non-linear density space. The averaged RMS and maximum errors of the proposed model were 1.1 and 3.1%,
respectively, in the above range. 相似文献
8.
Kimata M Terashima T Kurita N Satsukawa H Harada A Kodama K Sato A Imai M Kihou K Lee CH Kito H Eisaki H Iyo A Saito T Fukazawa H Kohori Y Harima H Uji S 《Physical review letters》2010,105(24):246403
We report the results of the angular-dependent magnetoresistance oscillations (AMROs), which can determine the shape of bulk Fermi surfaces (FSs) in quasi-two-dimensional (Q2D) systems, in a highly hole-doped Fe-based superconductor KFe2As2 with Tc ≈ 3.7 K. From the AMROs, we determined the two Q2D FSs with rounded-square cross sections, correspond to 12% and 17% of the first Brillouin zone. The rounded-squared shape of the FS cross section is also confirmed by the analyses of the interlayer transport under in-plane fields. From the obtained FS shape, we infer the character of the 3d orbitals that contribute to the FSs. 相似文献
9.
10.
Ohkoshi S Tokoro H Hozumi T Zhang Y Hashimoto K Mathonière C Bord I Rombaut G Verelst M Cartier dit Moulin C Villain F 《Journal of the American Chemical Society》2006,128(1):270-277
This article describes the studies of a photomagnetic cyanide-bridged Cu-Mo bimetallic assembly, Cu(II)(2)[Mo(IV)(CN)(8)].8H(2)O (Cu(II), S = (1)/(2); Mo(IV), S = 0) (1), which has an intervalence transfer (IT) band from Mo(IV)-CN-Cu(II) to Mo(V)-CN-Cu(I) around 480 nm. Wide-angle X-ray scattering and X-ray spectroscopic studies provide precise information about the 3D connectivity and the local environment of the transition metal ions. Irradiating with blue light causes solid 1 to exhibit a spontaneous magnetization (Curie temperature = 25 K). The thermal reversibility is carefully studied and shows the long-time stability of the photoinduced state up to 100 K. Photoreversibility is also observed; i.e., the magnetization is induced by irradiation with light below 520 nm, while the magnetization is reduced by irradiation with light above 520 nm. The UV-vis absorption spectrum after irradiation shows a decrease of the IT band and the appearance of the reverse-IT band in the region of 600-900 nm (lambda(max) = 710 nm). This UV-vis absorption spectrum is recovered to the original spectrum by irradiation with 658-, 785-, and 840-nm light. In this photomagnetic effect, the excitation of the IT band causes an electron transfer from Mo(IV) to Cu(II), producing a ferromagnetic mixed-valence isomer of Cu(I)Cu(II)[Mo(V)(CN)(8)].8H(2)O (Cu(I), S = 0; Cu(II), S = (1)/(2); Mo(V), S = (1)/(2)) (1'). 1' returns to 1 by irradiation of the reverse-IT band, which obeys the scheme for the potential energy surface in mixed-valence class II compounds. 相似文献