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51.
Over the past few years, a large number of studies have been prepared that describe the analysis of peptides and proteins using capillary electrophoresis (CE) and laser-induced fluorescence (LIF). These studies have focused on two general goals: (i) development of automatic, selective and quick separation and detection of mixtures of peptides or proteins; (ii) generation of new methods of quantitation for very low concentrations (nm and subnanomolar) of peptides. These two goals are attained with the use of covalent labelling reactions using a variety of dyes that can be readily excited by the radiation from a commonly available laser or via the use of noncovalent labelling (immunoassay using a labelled antibody or antigen or noncovalent dye interactions). In this review article, we summarize the works which were performed for protein and peptide analysis via CE-LIF. 相似文献
52.
M. Gastel J.S. Becker G. Küppers H.-J. Dietze 《Spectrochimica Acta Part B: Atomic Spectroscopy》1997,52(14):105-2059
A laser ablation system using a Nd:YAG laser was coupled both to a quadrupole inductively coupled plasma (ICP) mass spectrometer and to a double-focusing sector field ICP mass spectrometer. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for the determination of long-lived radionuclides in a concrete matrix. The investigated samples were two laboratory standards with a concrete matrix, which we doped with different long-lived radionuclides (e.g. 99Tc, 232Th, 233U, 237Np) from the ng g−1 to μ g−1 concentration range and an undoped concrete material (blank). Detection limits for long-lived radionuclides in the 10 ng g−1 range are reached for LA-ICP-MS using the quadrupole mass spectrometer. With double-focusing sector field ICP-MS, the limits of detection are in general one order of magnitude lower and reach the sub ng g−1 range for 233U and 237Np. A comparison of mass spectrometric results with those of neutron activation analysis on undoped concrete sample indicates that a semiquantitative determination of the concentrations of the minor and trace elements in the concrete matrix is possible with LA-ICP-MS without using a standard reference material. 相似文献
53.
A qualitative discussion on atom-surface elastic scattering taking place in the presence of laser radiation is given. It is suggested that appreciable effects of laser radiation on diffraction patterns may be expected if the laser radiation is capable of inducing electronic transitions in atoms with a large probability.Research sponsored by the Air Force Office of Scientific Research (AFSC), United States Air Force, under Contract No. F49620-78-C-0005, and the National Science Foundation under Grant No. CHE77-27826. The United States Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation hereon.Alfred P. Sloan Research Fellow, 1976–1980; Camille and Henry Dreyfus Teacher-Scholar, 1975–1980. 相似文献
54.
用恒电位电流衰减法及激光扫描光电化学显微技术研究了在于PH=12.5及13.8的模拟混凝土孔溶液中钢筋钝化化膜的生长动力学及相应的破坏过程,实验结果表明,钢筋钝化膜的生长过程存在两个主要阶段,各阶段膜厚均与生长时间存在正比对数关系,但当t<30秒和t>30秒时,膜的生长表出出不同的动力学特征,在钝化发生点蚀前,钝化膜的微区光电流一定的预兆,腐蚀抑制剂NaNO2影响膜的生长过程及膜厚,能提高钢筋的抗 相似文献
55.
Laser Doppler anemometry is used for the measurements of the plasma and particle velocity profiles in the coil region of an inductively coupled r.f. plasma. Results are reported for a 50 mm i.d. induction plasma torch operated at atmospheric pressure with argon as the plasma gas. The oscillator frequency is 3 MHz and the plate power is varied between 4.6 and 10.5 kW. Plasma velocity measurements are obtained using a fine carbon powder as a tracer. Measurements are also given for larger silicon particles (
) centrally injected into the discharge under different operating conditions.Nomenclature
d
p
particle diameter
-
P
0
plasma power
-
Q
1
powder carrier gas flow rate
-
Q
2
plasma gas flow rate
-
Q
3
sheath gas flow rate
-
r
distance in the radial direction
-
V
axial plasma velocity
-
V
p
axial particle velocity
-
Z
distance in the axial direction
-
standard deviation 相似文献
56.
利用激光光解装置检测了C60-地塞米松(C60-DE)的苯溶液在355 nm激光照射下产生的激发三重态, 3C60-DE*出现四个吸收峰, 分别位于700、440、350 和310 nm. 在330 nm处观察到了它的漂白吸收最大值, 这与其基态吸收最大值相对应. 3C60-DE*能够将能量转移给O2分子而淬灭. 与3C60*相比, 3C60-DE*的三重态鄄三重态(T-T)淬灭速率常数减小(3C60*为(5.03±1.31)×109 L·mol-1·s-1, 3C60-DE*为(3.53±0.87)×109 L·mol-1·s-1), 而寿命增加了(3C60*为(12.0±2.6) μs, 3C60-DE*为(18.0±3.3) μs), 这可能是C60分子上连接了地塞米松分子后减小了C60球之间碰撞的几率所致. 相似文献
57.
天线若丹明染料分子内能量与电荷传递的研究 总被引:2,自引:0,他引:2
染料三重态在染料激光的应用中起着重要作用,尤其是三重态一Z重态(T-T)吸收常常会造成谐振腔损耗*.为了减少由基态吸收而造成的话振腔损耗,带有紫外吸收天线分子的三发色团染料已在研究问,2,5·二苯基螨喳(PP0)在紫外区(如308删)有很强的吸收,PPO-rhod.系列染料(见图1)在紫外区的吸收就很强,由PPO到若丹明母体的单线态一单线态(S功能量传递使这类三发色团染料具有较大的荧光量子效率,较小的基态重复吸收耗能卜,司.然而,在610N640nm区域中这些天线若丹明染料的激光输出效率远远小于若丹明Rh630*,其原因正是… 相似文献
58.
Minoru Yamaji Ai Suzuki Fuyuki Ito Shozo Tero-Kubota Seiji Tobita Bronislaw Marciniak 《Journal of photochemistry and photobiology. A, Chemistry》2005,170(3):253-259
Photodissociation of the carbon-X (X = Br and Cl) bonds in p-bromo- and p-chloromethylbenzophenone (BMBP and CMBP) in solution were investigated by time-resolved EPR and laser flash photolysis techniques. BMBP and CMBP were found to undergo ω-bond cleavage to yield the p-benzoylbenzyl radical (BBR) at 295 K, and the quantum yields (ΦBBR) were determined. The CIDEP signal originated from BBR formed upon decomposition of CMBP was obtained while that for BMBP was absent. By using triplet sensitization of acetone, the efficiencies (BBR) of the CX bond fission in the triplet states of BMBP and CMBP were determined. The agreement between the ΦBBR and BBR values for CMBP indicates that the CCl bond dissociation occurs only in the triplet state. In contrast to CMBP, the cleavage of the CBr bond in BMBP upon direct excitation was concluded to be the event only in the excited singlet state without triplet formation, whereas the triplet state was also reactive for ω-bond dissociation. The rate of CBr bond dissociation seemed to be greater than that of intersystem crossing from the S1 to the T1 state. Schematic energy diagrams of the excited states of BMBP and CMBP were shown, and the reaction profiles were discussed from the viewpoint of the CX bond enthalpies. 相似文献
59.
Rainer P. H. Garten 《中国化学会会志》1994,41(3):259-274
Selected prominent problems in the analysis of advanced ceramic materials are surveyed. The importance of reliability of results is discussed in the field of elemental trace- and microanalysis in view of its interaction with economy, power of detection, local resolution and speciation selectivity. Particular problems in the analysis of major constituents, trace components and microlocal distributions are based on the striking propertics of ceramics; they are exemplified. Analytical assistance must start from the beginning of the production processing, in the preparation of the powdered base materials. Determination of the stoichiometry requires high accuracy and differentiation of chemical species in bulk and surface analysis of ceramic base powders. Element trace determination by direct instrumental methods requires standard reference materials for calibration; these are currently inavailable in a sufficient variety. For optimum reliability and power of detection, element traces must be prepared in isolated form in a small excitation volume for analysis. A review on the state-of-the-art of wet-chemical combined procedures is presented. Decomposition position procedures are emphasized, due to their risk of contributing severe systematic error. Combustion in elementary fluorine is presented for decomposition of refractory materials. The performance of some direct procedures is discussed. Very efficient methods are available for element trace determinations in ceramic materials, offering high detection power. Several approaches for high-resolution local microanalysis in non-conductive ceramic materials are identified as the most promising development in the analysis of sintered compact ceramic products and devices. 相似文献
60.