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131.
Mochida T Takazawa K Matsui H Takahashi M Takeda M Sato M Nishio Y Kajita K Mori H 《Inorganic chemistry》2005,44(23):8628-8641
Charge-transfer salts of branched-alkyl biferrocenes, (1',1' '-R2-1,1' '-biferrocene)[Ni(mnt)2] (1a, R = isopropyl; 2a, R = dineopentyl) and (1',1' '-R2-1,1' '-biferrocene)2[Co(mnt)2]2 (1b, R = isopropyl; 2b, R = dineopentyl), were prepared. Their valence states were investigated using X-ray crystallography and M?ssbauer spectroscopy. Complexes 1a and 1b show segregated-stack crystal structures that contain columns of acceptors, whereas structures of 2a and 2b, which contain bulky donors, are rather discrete. All of the complexes contain mixed-valent biferrocenium monocations. A two-step valence transition was found in complex 1a. The crystal contains two crystallographically independent cations: one undergoes valence localization below room temperature; the other undergoes valence localization below ca. 130 K. The former transition is derived from asymmetry of the crystal environment around the cation, whereas the latter one is caused by symmetry lowering coupled with a spin-Peierls transition (T(C) = 133.2 K) associated with the dimerization of the acceptors. This compound was found to exhibit a dielectric response based on valence tautomerization. Other complexes (1b, 2a, and 2b) show a valence-trapped state. In all complexes, charge localization was found to occur through local electrostatic interactions between the donor's cationic moiety and the acceptor's electronegative moieties. 相似文献
132.
Two tunneling frequencies were identified for methyl groups in hexamethylbenzene from 4.2 up to 30.9 K by means of the N.M.R. field cycling method. The frequencies were 9.6 ±- 0.4 MHz (A) and 7.9 ±- 0.4 MHz (B) at 4.2 K. The frequency A was almost independent of the temperature whereas the frequency B decreased as the temperature increased, the decrease being a linear function of T3. These facts indicate that the six methyl groups in hexamethylbenzene molecule are not independent but are coupled to one another rather strongly. 相似文献
133.
We investigated femtosecond and picosecond time-resolved fluorescence dynamics of a tetrameric fluorescent protein Kaede with a red chromophore (red Kaede) to examine a relationship between the excited-state dynamics and a quaternary structure of the fluorescent protein. Red Kaede was obtained by photoconversion from green Kaede that was cloned from a stony coral Trachyphyllia geoffroyi. In common with other typical fluorescent proteins, a chromophore of red Kaede has two protonation states, the neutral and the anionic forms in equilibrium. Time-resolved fluorescence measurements clarified that excitation of the neutral form gives the anionic excited state with a time constant of 13 ps at pH 7.5. This conversion process was attributed to fluorescence resonance energy transfer (FRET) from the photoexcited neutral form to the ground-state anionic form that is located in an adjacent subunit in the tetramer. The time-resolved fluorescence data measured at different pH revealed that excited-state proton transfer (ESPT) also occurs with a time constant of 300 ps and hence that the FRET and ESPT take place simultaneously in the fluorescent protein as competing processes. The ESPT rate in red Kaede was significantly slower than the rate in Aequorea GFP, which highly likely arises from the different hydrogen bond network around the chromophore. 相似文献
134.
[reaction: see text] Little is known about how quinoxaline-2-carboxylic acid (QC) is synthesized in nature. On the basis of analysis of echinomycin biosynthetic gene clusters as well as feeding experiments with labeled precursors, we have proposed a biosynthetic pathway to QC and identified the (2S,3S)-beta-hydroxytryptophan as a key intermediate. 相似文献
135.
Nakano M Kishi R Nakagawa N Ohta S Takahashi H Furukawa S Kamada K Ohta K Champagne B Botek E Yamada S Yamaguchi K 《The journal of physical chemistry. A》2006,110(12):4238-4243
The second hyperpolarizabilities of bisimidazole- and bistriazole-benzene compounds have been calculated at different levels of approximation to unravel the effects of diradical character as well as of charge and spin multiplicity. The largest second hyperpolarizabilities are associated with intermediate diradical character, provided positive charging does not compensate for this effect. For the neutral diradical bisimidazole compound, the singlet diradical species possesses a second hyperpolarizability two to three times larger than the corresponding triplet, demonstrating the possibility of spin state control of the third-order NLO responses for diradical species. 相似文献
136.
Ken Takayama Senri Soma Taiji Inoue Hideaki Kakinuma Takashi Haraguchi Kaoru Suzuki 《Applied Physics A: Materials Science & Processing》2010,101(4):727-733
Phosphorus-doped diamond-like carbon (DLC) films were deposited on quartz and p-type silicon (p-Si) substrates by pulsed-laser
deposition. Open-circuit voltage (V
oc) and short-circuit density (I
sc/cm2) from a heating process converted from one type of electrode to another and the two types of electrode pattern are shown
by the V–I characteristics. The first heating process was by a ceramic heater, and the other was by an infrared heater. We adopted two
electrode patterns, from a bipectinate electrode and a plot pattern electrode, to measure electric photovoltaic characteristics.
We were able to upgrade V
oc and I
sc/cm2 to 35∼45 mV, and 0.24 μA/cm2, respectively, under infrared heating. V
oc by the plot pattern electrode was over 2 V under infrared heating and ceramic heating did not match this on deposition by
the PLD method. 相似文献
137.
A combinatorial proof for the relation between the exponential function and the logarithmic function
Aequationes mathematicae - Two combinatorial identities are considered. These identities imply that $$\exp $$ and $$\log $$ are mutually inverse to one another even in the case where the variable... 相似文献
138.
We demonstrate that ultrasmall double-layer photonic-crystal-slab cavities exhibit a very high-Q value for a wide range of the layer spacing, which enables us to realize unique optomechanical coupling. By mechanically varying the separation, we can achieve extraordinarily large wavelength conversion. In addition, the light stored in the cavity can generate a large radiation force. We show that this system exhibits extremely high energy conversion efficiency between optical and mechanical energy, leading to a novel approach for the optomechanical control of light and matter. 相似文献
139.
Hideaki Matsunaga a & Satoru Murakami 《Journal of Difference Equations and Applications》2013,19(7):661-689
For nonlinear autonomous functional difference equations, the existence of the local stable manifolds, together with the local unstable manifolds and the local center-unstable manifolds, is shown. As an application, the principle of linearization which states that stabilities and instabilities for the zero solution of nonlinear equations can be derived from those of the zero solution of the linearized equations under some circumstances is established for functional difference equations. 相似文献
140.