The photo-induced electron and hole transfer across the semiconductor-dielectric interface in trap-dominated p-type organic field-effect transistors has been investigated. It has been observed that the transfer of electrons into the dielectric results in a decrease of the field-effect mobility of polarons, suggesting that additional shallow traps are generated in the conduction channel. Using this effect, the dependence of the field-effect mobility on the density of shallow traps, mu(N), has been measured, which allowed us to estimate the average polaron trapping time, tau_{tr}=50+/-10 ps, and the density of shallow traps, N0=(3+/-0.5) x 10(11) cm(-2), in the channel of single-crystal tetracene devices. 相似文献
A nonlinear theory is developed to study surface waves excited by the prescribed horizontal oscillation of the side wall of a circular basin. It is assumed that the frequency of the forced oscillation is near either one of the resonance frequencies of the water in the basin or twice of it. A multiple-scale asymptotic expansion is constructed to derive an equation for the amplitude of an excited eigenmode and critical points of some parameters are found for primary and subharmonic resonance waves. Across these critical points the eigenmode amplitude increases abruptly but remains bounded except at certain values of the water radius to the depth ratio where internal resonance appears. 相似文献
A linear theory is developed to study the forced capillary-gravity waves generated on water in a circular basin by the horizontal oscillations of its side wall. A Green's function method is used to construct a solution of the linearized equations subject to an edge condition at the contact line. The problem is reformulated in terms of an integral equation on the equilibrium free surface, and a uniqueness result is obtained by invoking the Fredholm's alternatives. 相似文献
In this paper, a piezoelectric analogy theorem is proposed, in which a piezoelectric body is represented as being composed of two fictitious bodies, an elastic body and a rigid dielectric body. An electric and elastic multipole approach for the treatment of various defects (dislocation, inhomogeneity, …) in finite piezoelectric media is then developed. It is shown that the electric and elastic coupling effects, the boundary effects, and the defects may be considered uniformly as sources of permanent and induced electric and elastic multipoles. 相似文献
We propose all‐dielectric metasurfaces that can be actively re‐configured using the phase‐change material Ge2Sb2Te5 (GST) alloy. With selectively controlled phase transitions on the composing GST elements, metasurfaces can be tailored to exhibit varied functionalities. Using phase‐change GST rod as the basic building block, we have modelled metamolecules with tunable optical response when phase change occurs on select constituent GST rods. Tunable gradient metasurfaces can be realized with variable supercell period consisting of different patterns of the GST rods in their amorphous and crystalline states. Simulation results indicate a range of functions can be delivered, including multilevel signal modulating, near‐field coupling of GST rods, and anomalous reflection angle controlling. This work opens up a new space in exploring active meta‐devices with broader applications that cannot be achieved in their passive counterparts with permanent properties once fabricated.
Chiral rhodium catalysts comprising 2,5‐diaryl‐ substituted bicyclo[2.2.1]diene ligands L1 – L10 were utilized in the enantioselective 1,4‐addition reaction of arylboronic acids to N‐substituted maleimides. In the presence of 2.5 mol % of RhI/ L2 , enantioenriched conjugate addition adducts were isolated in 72–99 % yields with 86–98 % ee. This protocol offers a convenient method to access a variety of 3‐arylsuccinimides in a highly enantioselective manner. Maleimides with readily cleavable N‐protecting groups were tolerated enabling the synthesis of useful synthetic intermediates. Pyrrolidine 4 , a biologically active compound, and pyrrolidine 5 , an ent‐precursor to an HSD‐1 inhibitor, were synthesized to demonstrate the utility of this method. 相似文献
Oxidative addition of Br2 to [Mn(CO)5]? leads to the formation of [(CO)4MnBr], followed by the ligand exchange of bromide to [S,Se-C6H3-4-Me]22? to form complex (CO)3Mn (µ-?4-SC6H3-4-(CH3)Se-SeC6H3-4-(CH3)S)Mn(CO)3 (1). A new five-coordinate complex [(CO)3Mn(-S,-Se-C6H3-4-CH3)]? (2) can be synthesized through two different routes: (a) oxidative addition of diselenide [HS,Se-C6H3-4-Me]2 to the [Mn(CO)5]? followed by deprotonation and ligand dissociation to generate complex 2; (b) reduction of diselenide bonds of complex 1 by [BH4]? to produce 2. Drop-wise addition of HBF4·OEt2 at 0 °C results in the formation of complex 1. The X-ray analysis shows that complex 2 has relative short Mn–Se and Mn–S bond distances compare to the published structures of cis-[(CO)4Mn(EPh)2]? (E = S and Se; Liaw et al. in J. Chin. Chem. Soc. 43:427–431, 1996; Liaw et al. in Inorg. Chem. 35:2530, 1996). Interestingly, exposure of the coordinated unsaturated complex 2 under CO(g) atmosphere resulted in complex cis-[(CO)4Mn(-S,-Se-C6H3-4-Me)]? (3) being formed. After purging the solution of complex 3 with N2, it was reconverted completely back to complex 2; this observation was characterized by FTIR. The cyclic voltammetry scan of complex 2 shows a quasi-reversible redox couple with E1/2 = ?1.94 V and Ipa/Ipc = 0.68. Ligand [HS, Se-C6H3-4-CH3]2 and complexes 1 and 2 are all characterized by IR, UV–Vis, NMR, EA and X-ray single crystal diffraction. 相似文献
With the increasing application of flip-chip technology in the microelectronics industry, the adhesion strength of interfaces
in flip-chip microelectronic structures has become an important issue for manufacturing and operation. In this paper we present
an experimental investigation of the adhesive strength of underfill material to solder mask coated FR-4 substrate under thermal
cycling. The effects of the number of thermal cycles on interfacial strength were investigated by using the button shear test.
The relationship between interfacial strength and the thickness of solder mask was also examined. Furthermore, the morphologies
of fracture surfaces of the test specimens were analyzed by scanning electron microscopy. The results of this study show that
the interfacial strength of the underfill/solder mask/substrate joint was significantly reduced by thermal fatigue. Finally,
the degradation behavior and possible mechanisms were then determined on the basis of these observations. 相似文献
Linear and nonlinear analyses of water waves in an elastic vessel are carried out to study the dramatic phenomena of Dragon
Wash as well as related controllable experiments. It is proposed that the capillary edge waves are generated by parametric
resonance, which is shown to be a possible mechanism for both rectangular an circular vessels. For circular vessel, the normal
geometric resonance is also operating, thus greatly enhance the dramatic effect. The mechanism of nonlinear mode-mode interaction
is proposed for the generation of axisymmetric low-frequency gravity waves by the high- frequency external excitation. A simple
model system is studied numerically to demonstrate explicitly this interaction mechanism. 相似文献
The newly manufactured N-isopropylacrylamide (NIPAM) polymer gel is composed of four components, i.e., gelatin, monomer (NIPAM), crosslinker (N,N’-methylenebisacrylamide, Bis), and antioxidant (tetrakis hydroxymethyl phosphonium chloride, THPC). In this study, we investigated
the effects of gel composition on the dose response of NIPAM polymer gel. A statistical experiment to analyze the contribution
of each composition to the linearity and sensitivity of NIPAM gel was performed. Results indicate that the amount of gelatin,
NIPAM (15.17%), Bis, and THPC have dominant effects on the sensitivity of the gel, with contributions of 59.73, 15.17, 10.64,
and 14.45%, respectively. The amount of gelatin and Bis mainly affected the linearity of the gel, with contributions of 44.70
and 50.99%, respectively. The linearity of most compositions of the gel was greater than 0.99 when (%C)/(%T) was lower than 8.0. Optimal (%C)/(%T) for higher sensitivity should be in the range of 4−9. The temporal stability experiment showed that the dose response curve
attained stability at about 5 h after irradiation and persisted up to 3 months. 相似文献