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111.
Kenji Kinashi Satoshi Nakamura Masaki Imamura Kenji Ishida Yasukiyo Ueda 《Journal of Physical Organic Chemistry》2012,25(6):462-466
The mechanism for negative photochromism of spiropyran in silica was investigated. Prior to our study, the chemical origin of the high thermal stability of the photomerocyanine form (PMC‐form) dispersed in perhydropolysilazane (PHPS), which is converted to silica at ambient temperature, had been investigated. The high thermal stability of the PMC‐form is attributed to the protonated PMC‐form (H???PMC‐form), which is produced by intermolecular hydrogen bonding between oxide anions generated by the cleavage of the C ? O bonds and the partially uncondensed Si ? OH and O ? H bonds of silica. Furthermore, the H???PMC‐form could be thermally isomerized from the SP‐form without UV light irradiation. This specific phenomenon is caused by the so‐called negative photochromism. In this study, we proposed a mechanism for negative photochromism according to the relationship of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The relationship between the HOMOs was determined using cyclic voltammetry (CV) and ultraviolet photoelectron spectroscopy (UPS). On the other hand, the relationship between the LUMOs was determined from the respective optical bandgap. As a result, the HOMO level of H???PMC‐form was ?6.1 eV and that of SP‐form was ?5.3 eV. Accordingly, the thermodynamic stabilization of H???PMC‐form was attributed to the thermal isomerization through negative photochromism from the SP‐form. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
112.
113.
D. Nakamura K. Tamaru T. Akiyama A. Takahashi T. Okada 《Applied Physics A: Materials Science & Processing》2008,92(4):767-772
The dynamics of debris from the laser-produced tin (Sn) plasma was investigated for an extreme ultraviolet light source in
order to establish the guideline for the optimum design of a mitigation system, such as a mass-limited target. The dissemination
of the Sn atoms from the different shapes of a wire and a mass-limited droplet target were investigated using the laser-induced
fluorescence (LIF) imaging method. The Sn droplet targets with a diameter in the range of 5 to 17 μm were prepared by a new
droplet generating technique using a pulsed laser. There was a large difference in the angular distribution of Sn atoms in
the plane parallel and perpendicular to the wire axis, indicating the curvature of the target surface governed the angular
distribution of the ablated species. The spatial distributions of Sn atoms from the droplet targets were similar to those
from the curved surface of the wire targets. The ablation dynamics of the droplet observed by a high-speed imaging camera
is also discussed. 相似文献
114.
N. Shinohara H. Osawa Y. Okamoto Y. Nakamura K. Miura H. Muraoka Y. Nakamura 《Journal of magnetism and magnetic materials》2008
The bit-error rate (BER) performance of the generalized partial response maximum likelihood with autoregressive (GPRML-AR) channel model system in perpendicular magnetic recording (PMR) channel with thermal decay is obtained. The 128/130(0,16/8) run-length-limited (RLL) code is used as a recording code. The GPR channel consists of the PR1 channel followed by the reduction circuit of predicted noise. The BER performance is evaluated by computer simulation using a thermal decay model. The model has been obtained by using an approximate equation that represents amplitude degradation of the reproducing waveform with elapsed time based on the experimental data for CoPtCr-SiO2 PMR media. The Viterbi detector with an AR channel model is employed. Furthermore, long-term degradation of the required SNR to achieve a BER of 10−4 with elapsed time is obtained and the performance is compared with that of PR1ML system. The results show that the poorer the thermal stability of the medium becomes, the larger the SNR gain of the GPR1ML-AR system over the PR1ML system becomes. The SNR gain also increases with elapsed time. 相似文献
115.
Yasuda K Torii T Yasui K Iida Y Tuziuti T Nakamura M Asakura Y 《Ultrasonics sonochemistry》2007,14(6):699-704
The ultrasonic reactor with dual frequency was used and the effect of frequency on the fluorescence intensity of terephthalate ion was experimentally investigated in the frequency range from 176 to 635 kHz. The sonochemical reaction fields were visualized by using sonochemical luminescence of luminol solution. Compared with the fluorescence intensity of terephthalate ion for single frequency, the fluorescence intensity for dual frequency increased. The fluorescence intensity ratio of dual frequency to single frequency had maximum value when the frequency of transducer attached at the bottom wall was comparable in magnitude to that at the side wall. In the case of dual frequency, the sonochemical reaction fields became more extensive in the reactor and more intensive around the center of the reactor. 相似文献
116.
Takeyuki Kikuchi Tatsuya Nakamura Makoto Nakanishi Jun Takada 《Journal of magnetism and magnetic materials》2010,322(16):2381-2385
Magnetic properties of La-Co substituted M-type strontium hexaferrites were studied. The samples were prepared by polymerizable complex method. Crystal structure of samples has been investigated by powder X-ray diffraction (XRD). Single-phase M-type strontium hexaferrites with chemical composition of Sr1.05−xLaxFe12−xCoxO19 (x=0-0.4) were formed by heating at 1173 K for 24 h in air. Magnetic properties were discussed by measurements of M-H curves with vibrating sample magnetometer (VSM). La-Co substituted M-type strontium hexaferrites prepared by polymerizable complex method showed typical magnetic hysteresis of hard ferrite. The coercive force increased significantly by La-Co substitution with polymerizable complex method. Maximum coercive force achieved in this study is 8.0 kOe (640 kA/m). Scanning electron microscopy revealed that the prepared ferrite particles have plate-like shape of diameter range between 20 and 500 nm. 相似文献
117.
Tsuchiya H Enoto T Yamada S Yuasa T Kawaharada M Kitaguchi T Kokubun M Kato H Okano M Nakamura S Makishima K 《Physical review letters》2007,99(16):165002
A report is made on a comprehensive observation of a burstlike gamma-ray emission from thunderclouds on the Sea of Japan, during strong thunderstorms on 6 January 2007. The detected emission, lasting for approximately 40 sec, preceded cloud-to-ground lightning discharges. The burst spectrum, extending to 10 MeV, can be interpreted as consisting of bremsstrahlung photons originating from relativistic electrons. This ground-based observation provides the first clear evidence that strong electric fields in thunderclouds can continuously accelerate electrons beyond 10 MeV prior to lightning discharges. 相似文献
118.
119.
K. Yoshimura M. Takigawa Y. Takahashi H. Yasuoka M. Mekata Y. Nakamura 《Journal of magnetism and magnetic materials》1987,70(1-3):11-13
The nuclear spin-lattice relaxation rate, 1/T1, has been measured in weak itinerant ferromagnets Y(Co1−xAlx)2. The temperature and magnetic field dependence of 1/T1T has been found to be well described by the self-consistent renormalization (SCR) theory of spin fluctuations. The parameters characterizing spin fluctuations in this system were estimated from NMR and magnetic measurements. The temperature dependence of susceptibility calculated from these parameters well reproduces the experimental results. 相似文献
120.
H. Wada H. Nakamura K. Yoshimura M. Shiga Y. Nakamura 《Journal of magnetism and magnetic materials》1987,70(1-3):134-136
On the basis of the results of thermal expansion and NMR measurements, the stability of Mn moments and spin fluctuations in RMn2 are discussed. It has been shown that the interatomic distance of RMn2 plays a crucial role in determining the Mn magnetism in RMn2. 相似文献