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31.
X-ray reflectivity (XRR), X-ray fluorescence (XRF) and small angle X-ray scattering (SAXS) techniques are used to the monitoring of Cu/porous low κ processes, which are developed for the next generation (≤65 nm) integrated circuits. Sensitivity of XRR and XRF is sufficient to detect drifts of the copper barrier layer, copper seed layer and Cu CMP (chemical-mechanical polishing) processes. Their metrology key parameters comply with production requirements. SAXS allows determining the pore structure of low κ films: average pore size and pore size distribution. 相似文献
32.
The mechanism of X-ray waveguide-resonance propagation or the radiation superstream model, which can become the ground of X-ray nanophotonics, is discussed briefly. Some attention is devoted to features consideration of the simplest devices characterized by the waveguide-resonance transportation of X-ray beams. The experimental data showing the user possibilities of a simplest waveguide-resonators application for diffractometry are presented. We discuss the main reasons to improve the metrological characteristics for total reflection X-ray fluorescence (TXRF) analytical method in case when the target exciting beam is formed by a waveguide-resonator. Some problems appearing during the waveguide-resonator application are formulated. 相似文献
33.
Applied Biochemistry and Biotechnology - 相似文献
34.
S. M. Arabei D. V. Novik T. A. Pavich K. N. Solov’ev 《Journal of Applied Spectroscopy》2006,73(4):511-521
We have studied the fluorescence and fluorescence excitation spectra at 300 K, 77 K, and 4.2 K for silicate gel matrices colored
with meso-tetrapropylporphin by impregnation of the matrix with a solution of the pigment. Comparison of the data obtained
with the absorption spectra in acidified solutions and analysis of the low-temperature fine-structure vibronic spectra, and
also taking into account data obtained earlier for octaethylporphin in a xerogel showed formation of two cationic forms of
meso-tetrapropylporphin in the gel matrix: the short-wavelength form has a dicationic structure, while the long-wavelength form
has a monocationic structure. We have traced out the correlations of the vibrational structure in the spectra of the dicationic
form with data for the porphin dication, and we have drawn a number of conclusions concerning the normal vibrational modes
that are active in the vibronic fluorescence and absorption spectra of the studied cationic forms. Using the AM1 semiempirical
quantum chemical method, we optimized the geometry of the mesotetrapropylporphin dication: the most stable of the possible
conformers is the dication structure with saddleshaped macrocycle nonplanarity.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 453–461, July–August, 2006. 相似文献
35.
The aggregation of dansyl chloride (DNS-Cl) in acetone has been studied in detail by steady-state fluorescence techniques.It has been demonstrated that DNS-Cl is stable in acetone during purification and aggregation study processes.The aggregates are not solvolyzed in acetone,and do not take part n any chemical reactions either.It has been found that DNS-Cl tends to aggregate even when its concentration is much lower than its solubility in acetone.The aggregation is reversible,and both the aggregation and the deaggregation are very slow processes.Introduction of SDS has a positive effect upon the formation and stabilization of the aggregates. 相似文献
36.
37.
Yoshio Umezawa 《化学:亚洲杂志》2006,1(3):304-312
Lately, scientists have explored approaches to developing fluorescent and/or bioluminescent indicators to pinpoint cellular processes in single living cells. These analytical methods have become a key technology for visualizing and detecting what was otherwise unseen in live cells. The target signaling included second messengers, protein phosphorylations, protein–protein interactions, and protein localizations. 相似文献
38.
J. P. S. Farinha J. M. G. Martinho H. Xu M. A. Winnik R. P. Quirk 《Journal of Polymer Science.Polymer Physics》1994,32(9):1635-1642
Cyclization of a polystyrene chain (Mn = 10,600; Mw/Mn = 1.09) both ends labeled with 4-(1-pyrenyl)butanoamide groups was studied in cyclohexane between 25 and 95°C. The amide groups (peptide bonds) at both ends can form an intrachain hydrogen bond between the amide hydrogen at one chain end and the carbonyl oxygen at the other. The presence of two sets of conformers, random coils, and chains cyclized through hydrogen bonding, complicates the data analysis. The pyrene excimer kinetics of this polymer is well described by a model composed of two monomers (hydrogen bonded and nonbonded chains) and one excimer, in equilibrium. The cyclization rate constant for hydrogen-bonded chains is larger than the one for nonhydrogen-bonded chains. The pyrene excimer binding energy (ca. 1.6 kcal/mol) is lower than the published value for nonhydrogen-bonded chains (~ 9 kcal/mol), suggesting that intrachain hydrogen bonding hinders the stabilization of the excimer. © 1994 John Wiley & Sons, Inc. 相似文献
39.
Ildikó Mohammed-Ziegler Ferenc Billes 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(1-2):19-42
This review summarizes different applications of optical spectroscopic methods in calixarene chemistry including UV/Vis spectrometry,
vibrational spectroscopic techniques (FTIR and Raman spectroscopy), luminescence spectroscopy (including fluorescence and
phosphorescence), ellipsometry and various optical microscopic methods. Moreover, the results of theoretical studies (AM1,
PM3, DFT, ab initio, etc.) are summarized based on selected papers in the field of conformational studies, thermodynamics and complexation features.
About 300 references are processed systematically from the results reported mainly in the recent years with emphasis on the
potential of practical application of these molecules. 相似文献
40.
In order to study cross flow induced vibration of heat exchanger tube bundles, a new fluid–structure interaction model based on surface vorticity method is proposed. With this model, the vibration of a flexible cylinder is simulated at Re=2.67 × 104, the computational results of the cylinder response, the fluid force, the vibration frequency, and the vorticity map are presented. The numerical results reproduce the amplitude‐limiting and non‐linear (lock‐in) characteristics of flow‐induced vibration. The maximum vibration amplitude as well as its corresponding lock‐in frequency is in good agreement with experimental results. The amplitude of vibration can be as high as 0.88D for the case investigated. As vibration amplitude increases, the amplitude of the lift force also increases. With enhancement of vibration amplitude, the vortex pattern in the near wake changes significantly. This fluid–structure interaction model is further applied to simulate flow‐induced vibration of two tandem cylinders and two side‐by‐side cylinders at similar Reynolds number. Promising and reasonable results and predictions are obtained. It is hopeful that with this relatively simple and computer time saving method, flow induced vibration of a large number of flexible tube bundles can be successfully simulated. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献