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51.
为了满足超辐射发光管的短波长应用,采用InAlGaAs/AlGaAs量子点有源区和干法刻蚀工艺制备了短波长弯曲波导超辐射发光管。在1.6A脉冲电流注入下,器件峰值输出功率为29mW,中心波长为880nm,光谱半高宽为20.3nm。比较了干法刻蚀工艺和湿法腐蚀工艺对超辐射发光管器件性能的影响。在1.6A脉冲电流注入下,湿法腐蚀制备的器件峰值输出功率仅为7mW。与湿法腐蚀相比,干法刻蚀可以精确控制波导形状和参数,降低波导损耗,有效增大器件输出功率。 相似文献
52.
During the course of our investigation of the electron transfer properties of some redox species through highly hydrophobic
long chain alkanethiol molecules on gold in aqueous and non-aqueous solvents, we obtained some intriguing results such as
unusually low interfacial capacitance, very high values of impedance and film resistance, all of which pointed to the possible
existence of a nanometer size interfacial gap between the hydrophobic monolayer and aqueous electrolyte. We explain this phenomenon
by a model for the alkanethiol monolayer—aqueous electrolyte interface, in which the extremely hydrophobic alkanethiol film
repels water molecules adjacent to it and in the process creates a shield between the monolayer film and water. This effectively
increases the overall thickness of the dielectric layer that is manifested as an abnormally low value of interfacial capacitance.
This behaviour is very much akin to the ‘drying transition’ proposed by Lum, Chandler and Weeks in their theory of length
scale dependent hydrophobicity. For small hydrophobic units consisting of apolar solutes, the water molecules can reorganize
around them without sacrificing their hydrogen bonds. Since for an extended hydrophobic unit, the existence of hydrogen bonded
water structure close to it is geometrically unfavourable, there is a net depletion of water molecules in the vicinity leading
to the possible creation of a hydrophobic interfacial gap. 相似文献
53.
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55.
Jana Kocbov Frantiek Vavrek tpnka Novkov Lachmanov Jakub ebera Michal Valek Magdalna Hromadov 《Molecules (Basel, Switzerland)》2022,27(23)
Self-assembled monolayers (SAMs) of terpyridine-based transition metal (ruthenium and osmium) complexes, anchored to gold substrate via tripodal anchoring groups, have been investigated as possible redox switching elements for molecular electronics. An electrochemical study was complemented by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) methods. STM was used for determination of the SAM conductance values, and computation of the attenuation factor β from tunneling current–distance curves. We have shown that SAMs of Os-tripod molecules contain larger adlayer structures compared with SAMs of Ru-tripod molecules, which are characterized by a large number of almost evenly distributed small islands. Furthermore, upon cyclic voltammetric experimentation, Os-tripod films rearrange to form a smaller number of even larger islands, reminiscent of the Ostwald ripening process. Os-tripod SAMs displayed a higher surface concentration of molecules and lower conductance compared with Ru-tripod SAMs. The attenuation factor of Os-tripod films changed dramatically, upon electrochemical cycling, to a higher value. These observations are in accordance with previously reported electron transfer kinetics studies. 相似文献
56.
Jingjing Xu Yidong Lu Baohong Liu Chunhe Xu Jilie Kong 《Journal of Solid State Electrochemistry》2007,11(12):1689-1695
An ultrathin, ordered, and packed protein film, consisting of the 2-mercaptoacetic acid (MAA), polydimethyldiallylammonium
chloride (PDDA), and wild-type (WT) photosynthetic reaction center (RC; termed as WT-RC) or its pheophytin (Phe)-replaced
counterpart (termed as Phe-RC), was fabricated by self-assembling technique onto gold electrode for facilitating the electron
transfer (ET) between RC and the electrode surface. Near-infrared (NIR)-visible (Vis) absorption and fluorescence (FL) emission
spectra revealed the influence of pigment substitution on the cofactors arrangement and excitation relaxation of the proteins,
respectively. Square wave voltammetry (SWV) and photoelectric tests were employed to systematically address the differences
between the WT-RC films and mutant ones on the direct and photo-induced ET. The electrochemical results demonstrated that
ET initiated by the oxidation of the primary donor (P) was obviously slowed down, and the formed P+ had more population as well as more positive redox potential in the Phe-RC films compared with those in the WT ones. The
photoelectrochemical results displayed the dramatically enhanced photoelectric performances of the mutant ones, further suggesting
the slow-down formation of final charge-separated state in Phe-RC. The functionalized protein films introduced in this paper
provided an efficient approach to sensitively probe the redox cofactors and ET differences resulting from only minor changes
in pigment arrangement in the pigment–protein complex. The favored ET process observed for the membrane proteins RC was potentially
valuable for a deep understanding of the multi-step biological ET process and development of versatile bioelectronic devices. 相似文献
57.
G. Fonder J. Delhalle M. Essahli B. Ameduri Z. Mekhalif 《Surface and interface analysis : SIA》2008,40(2):85-96
Self‐assembly on a polycrystalline aluminum substrate of two sulfur‐containing alkylphosphonic acids, CH3? (CH2)11? S? (CH2)2? PO(OH)2, and CF3? (CF2)7? (CH2)2? S? (CH2)2? PO(OH)2, has been compared with CH3? (CH2)15? PO(OH)2. The reaction of the phosphonic head groups with the hydroxyls at the alumina surface to form phosphonates was studied with X‐ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection‐absorption spectroscopy (PM‐IRRAS). Barrier effects of the resulting layers was assessed by electrochemical polarization curves. With the conditions used in the present work for the self‐assembly reaction, it appears that the sulfur‐containing molecules do not perform as well as CH3? (CH2)15? PO(OH)2 in terms of film quality. Questions are raised about the possibility that the sulfur‐containing molecules could undergo cleavage during surface modification. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
58.
Dominique Langevin Dr. 《Chemphyschem》2008,9(4):510-522
This paper reviews the properties of aqueous foams. The current state of knowledge is summarized briefly and the interdisciplinary aspects of this field of investigation are emphasized. Many phenomena are controlled by physical laws, but they are highly dependent upon the chemicals used as foam stabilizers: surfactants, polymers, particles. Most of the existing work is related to surfactants and polymer foams, and little is known yet for particle foams although research in this field is becoming popular. This article presents the general concepts used to describe the monolayers and the films and also some of the recent advances being made in this area. 相似文献
59.
M. Manolova V. Ivanova D.M. Kolb H.-G. Boyen P. Ziemann M. Büttner A. Romanyuk P. Oelhafen 《Surface science》2005,590(2-3):146-153
In this study we describe details of a new technique that allows to deposit metal on top of a self-assembled monolayer (SAM). Monoatomic high platinum islands were formed on a 4-mercaptopyridine SAM on Au(1 1 1) by first immersing the SAM-covered gold electrode in an aqueous solution of K2PtCl4 without potential control to allow Pt(II) ions to form a complex with the pyridine nitrogen. The complexed Pt(II) ions were then reduced electrochemically to Pt(0) after transferring the electrode to a Pt(II) ion-free solution. Upon reduction, monoatomic high Pt islands were observed in STM, the total coverage depending on the time for complexation. Ex situ angle-resolved XPS studies reveal that the Pt islands indeed reside on top of the SAM. 相似文献
60.
Xiao‐Lin Wang Yan‐Dong He Li‐Yan You Zhong‐Yuan Lu Ze‐Sheng Li 《Journal of Polymer Science.Polymer Physics》2009,47(4):353-365
Dissipative particle dynamics simulations are applied to investigate the monolayer and multilayer film formations on different solid substrates by physical deposition. The influences of the polymer concentration, the polymer chain length, the solvent quality, and the interactions between the polymer solution and the solid substrate surface on the film formation dynamics and the mechanism are studied in detail. The results are analyzed in terms of the thickness and the shape of the deposited film, the kinetics of phase separation in the polymer solution, and the contact angle formed between the polymer aggregations and the substrate surface. Moreover, we suggest two strategies, designing a deposition process analogous to “chemical titration” and physically blocking interlayer diffusion by a simple crosslinked network barrier, to deposit the compact monolayer and multilayer films with better quality, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 353–365, 2009 相似文献