Contribution to the atomic absorption spectrophotometry of magnesium in the air-acetylene flame

Summary Non-sufficient attention seems to have been paid to the influence of various ions on the atomic absorption spectrophotometric determination of magnesium. SiO₃ ²⁺, Al³⁺, Be²⁺, Zr(IV), Ti(IV) decrease remarkably the Mg absorbance in air-acetylene flames, but the most interesting positive or negative effects on the absorbance of magnesium are exhibited in ternary systems of ions. 5-Sulphosalicylic acid protects magnesium in the presence of the above mentioned elements in binary or ternary ion systems and makes the atomic absorption spectrophotometric determination of magnesium possible in the presence of these ions.

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Zur atomabsorptionsspektrophotometrischen Bestimmung von Magnesium in der Luft-Acetylen-Flamme

Zusammenfassung Den verschiedenen Beeinflussungen durch Kationen und Anionen bei der atomabsorptionsspektrophotometrischen Bestimmung von Magnesium wurde bisher nur unzureichende Aufmerksamkeit gewidmet. Vor allem SiO₃ ^2–, Al³⁺, Be²⁺, Zr(IV), Ti(IV) üben einen merklichen negativen Einfluß auf die Absorption von Magnesium in der Acetylen-Luft-Flamme aus. Von besonderer Bedeutung sind verstärkte negative bzw. positive Einflüsse in ternären Ionensystemen, die die Resultate stark beeinträchtigen können. 5-Sulfosalicylsäure eignet sich im allgemeinen gut zur Aufhebung des störenden Ioneneinflusses bei der Bestimmung von Magnesium neben den oben genannten Elementen in binären oder ternären Systemen in Acetylen-Luft-Flammen.

     

Nanoscale focusing of atoms with a pulsed standing wave

We have theoretically and experimentally investigated the focusing properties of a detuned pulsed standing wave onto a beam of neutral atoms. In close analogy to the continuous-wave situation the dipole force leads to a periodic focusing of atoms with a period of λ/2, provided an adiabatic condition is fulfilled. Pulsed laser light is conveniently converted to short wavelengths and hence offers advantages in the application of atom lithography with elements of technological interest having blue or UV resonance lines. Received: 6 October 1999 / Revised version: 3 February 2000 / Published online: 5 April 2000     

Atom lithography with a cold, metastable neon beam

We study different aspects of atom lithography with metastable neon atoms. Proximity printing of stencil masks is used to test suitable resists that are sensitive to the internal energy of the atoms, including dodecanethiols on gold and octadecyltrichlorosilanes grown on a SiO₂ surface. As an example of patterning the atomic beam with laser light, we create parallel line structures on the surface with a periodicity of half the laser wavelength by locally de-exciting the atoms in a standing quenching wave. Received: 29 June 1999 / Revised version: 30 August 1999 / Published online: 10 November 1999     

Realignment process of actin stress fibers in single living cells studied by focused femtosecond laser irradiation

Three-dimensional dissection of a single actin stress fiber in a living cell was performed based on multi-photon absorption of a focused femtosecond laser pulse. The realignment process of an actin stress fiber was investigated after its direct cutting by a single-shot femtosecond laser pulse irradiation by high-speed transmission and fluorescence imaging methods. It was confirmed that mechanical force led by the femtosecond laser cutting propagates to entire cell through the cytockelton in a 100 μs time scale. The cut actin stress fiber was realigned in the time scale of a few tens of minutes. The dynamic analysis of the realignment induced by single-shot femtosecond laser gives new information on cell activity.     

Fast wavelength-tunable ultra-violet laser source for confocal Fura-2AM imaging

We report a novel wavelength-flexible laser source for three-dimensional ultra-violet imaging. Based on supercontinuum generation in photonic crystal fiber, the resultant broadband laser source extended from λ = 331 nm into the visible region of the spectrum. Using an electronically-controlled filter wheel and filter set with a response time of approximately 50 ms, rapid wavelength selection was performed. The described scheme is capable of exciting the current range of ultra-violet-excited fluorophores and the simple and rapid wavelength control also provides a new approach for fast ratiometric imaging of Fura-2AM, facilitating an easy method of performing quantitative intracellular calcium concentration measurements.     

High Performance Small Optically Pumped Caesium Beam Frequency Standard

An experiment of a high performance small optically pumped caesium （Cs） beam frequency standard is reported. An extended cavity diode laser works as the probing laser, of which the frequency is stabilized by the Zeeman modulation method. The running parameters of the frequency standard are dynamically optimized via digital servo electronics. The experimental setup improves the frequency stability up to 1.8 × 10^-12 at T = 1 s and about 1.0 × 10^-13 at T= 10^5s （Allan deviation）     

A simple wet-chemical synthesis and characterization of CuO nanorods

Using a simple wet-chemical route, we synthesized CuO nanorods with diameters of ca. 5–15 nm and lengths of up to 400 nm. The purity, crystallinity, morphology, structure features, and chemical composition of the as-prepared CuO nanorods were investigated by powder X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Received: 22 March 2002 / Accepted: 12 June 2002 / Published online: 28 October 2002 RID="*" ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn     

乙酰丙酮在低温电热蒸发ICP-AES中的化学改进作用机理研究

近年来 ,低温蒸发技术的研究和应用引起了人们的重视 [1～ 3 ] .我们 [4]曾报道应用乙酰丙酮试剂作化学改进剂 ,于石墨管中低温 (～ 75 0℃ )蒸发铍的乙酰丙酮螯合物的 ETV-ICP-AES法 ,并用于人发中痕量铍的测定 .本文从机理上探讨了待测物 (铍或铬 )在石墨管中的蒸发及传输形式 ;研究了相应的乙酰丙酮螯合物的生成条件及主要影响因素 ;在此基础上得出在低温蒸发条件下相应的规律 .1　实验部分1.1　仪器装置　所用的 ICP-AES仪器、电热蒸发装置及它们之间的连接与文献 [1,4]相同 .紫外 -可见分光光度计 (日本岛津 UV-2 0 0 0 ) ,仪器…