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341.
Intense chiroptical properties and efficient reversibility of the chemical redox cycle support the adaptability of the CuI/CuII complex system 1 / 2 for the development of a binary molecular device. Reduction proceeds with ascorbic acid, and oxidation with ammonium persulfate. 相似文献
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A. Milekhin M. Friedrich D.R.T. Zahn L. Sveshnikova S. Repinsky 《Applied Physics A: Materials Science & Processing》1999,69(1):97-100
Structures with CdS quantum dots produced by the Langmuir–Blodgett (LB) technique were investigated by Raman, IR, and UV spectroscopies.
The confinement effect of longitudinal optical (LO) phonons in CdS quantum dots was investigated by Raman spectroscopy. Surface
vibrational modes of CdS quantum dots were observed in IR spectra. It was shown experimentally that the frequency of the surface
vibrational modes depends on the properties of the surrounding media. An average size of CdS quantum dots of about 3–6.4 nm
was obtained from the analysis of UV measurements.
Received: 1 February 1999 / Accepted: 1 April 1999 / Published online: 19 May 1999 相似文献
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346.
Maurício Zahn 《International Journal of Mathematical Education in Science & Technology》2017,48(6):963-971
This paper presents an interesting deduction of the Golden Spiral equation in a suitable polar coordinate system. For this purpose, the concepts of Golden Ratio and Golden Rectangle, and a significant result for the calculation of powers of the Golden Ratio ? using terms of the Fibonacci sequence are mentioned. Finally, various geometrical considerations that help us deduce the sought equation are presented. 相似文献
347.
Cobalt Boryl Complexes: Enabling and Exploiting Migratory Insertion in Base‐Metal‐Mediated Borylation
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Dr. René Frank James Howell Jésus Campos Rémi Tirfoin Nicholas Phillips Dr. Stefan Zahn Prof. Dr. D. Michael P. Mingos Prof. Dr. Simon Aldridge 《Angewandte Chemie (International ed. in English)》2015,54(33):9586-9590
Cobalt boryl complexes, which have only been sporadically reported, can be accessed systematically with remarkable (but controllable) variation in the nature of the M? B bond. Complexes incorporating a very strong trans σ‐donor display unparalleled inertness, reflected in retention of the M? B bond even in the presence of extremely strong acid. By contrast, the use of the strong π‐acceptor CO in the trans position, results in significant Co? B elongation and to labilization of the boryl ligand via unprecedented CO migratory insertion. Such chemistry provides a pathway for the generation of coordinative unsaturation, thereby enabling ligand substitution and/or substrate assimilation. Alkene functionalization by boryl transfer, a well‐known reaction for noble metals such as Rh or Pt, can thus be effected by an 18‐electron base‐metal complex. 相似文献
348.
Y. Sakurai G. Salvan Y. Hosoi H. Ishii Y. Ouchi K. Seki T. U. Kampen D. R. T. Zahn 《Applied Surface Science》2002,190(1-4):382-385
The interaction between Alq3 and potassium was studied by using Raman and infrared spectroscopies. Infrared reflection absorption spectroscopy (IRRAS) spectra of Alq3 films show significant changes after potassium deposition, such as the appearance of new bands and changes in relative intensity. Surface-enhanced Raman scattering (SERS) spectra obtained using the 413.1 nm line of a Kr+ laser reveal similar changes. Changes are even more obvious when the 530.9 nm line was used for excitation. Changes in the SERS for excitation with the 413.1 nm line are less obvious due to a strong photoluminescence. The vibrational pattern of potassium-doped Alq3 cannot be explained by the formation of radical anion by simple charge transfer, indicating the excess electron is not delocalized over the molecule. The observed spectral change suggests that the potassium atom interacts with both nitrogen and oxygen atoms of Alq3 molecule. 相似文献
349.
Nitrides of refractory metals are investigated as diffusion barriers for Cu metallization. The composition, thermal stability
and inter diffusion in layered systems are characterized by depth profile analysis. For the quantification of depth profiles
determination of sensitivity factors is essential. For nitrogen and other light elements matrix specific standards are often
not available and compound standards are used for calibration. We have investigated the systems Ta–N and Ta–Si–N and for comparison
Cr–N by means of Auger electron spectrometry (AES) and glow discharge optical emission spectrometry (GDOES). A non-linear
calibration curve for the N/Cr intensity ratio was observed with GDOES in the Cr–N-system, probably caused by self-absorption
of the Cr line. 相似文献
350.
Valence band photoemission spectroscopy (VB-PES) and inverse photoemission spectroscopy (IPES) were employed to determine the occupied and unoccupied density of states upon silver deposition onto layers of two phthalocyanines (H2Pc and CuPc). The two different Pc molecules give rise to very distinct behaviour already during the initial stage of silver deposition. While in the CuPc case no shift occurs in the energy levels, the H2Pc highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are shifting simultaneously by 0.3 eV, i.e., the HOMO shifts away from the Fermi level while LUMO shifts towards the Fermi level. As the silver quantity increases the HOMO levels of both Pcs are shifting towards the Fermi level. When the Fermi level is resolved in the VB spectra, the characteristic features of H2Pc and CuPc are smeared out to some extent. Shifts in HOMO and LUMO energy positions as well as changes in line shapes are discussed in terms of charge-transfer and chemical reactions at the interfaces. 相似文献