电热原子化机理研究——Ⅰ.测定原子化过程活化能的新方法

本文提出了用正态分布函数模拟时间-信号轮廓;建立了测定原子化过程动力学参数的模型。此法有效地消除了由Sturgeon法、AKMAN法所得的Arrehenius曲线的非线性,为原子化过程动力学参数的准确测定打下了基础。并结合热力学方法,对镍、银、砷、铋的原子化机理进行了探讨。     

U与O2，CO2的升温反应行为

采和程序升温分析技术研究了铀与O2，CO2(氩气为惰性介质)的程序升温反应动力学行为，通过XRD对动力学中间过程及最终的物相进行了阶段性分析。     

Cd(Ⅲ)、Co(Ⅲ)、Cu(Ⅲ)与异烟酸的配合物合成与性质

以异烟酸为配体合成了Cd(Ⅱ)、Co(Ⅱ)、Cu(Ⅱ)3种配合物,用X-射线单晶衍射研究了其结构,3种配合物具有类似的六配位结构,由于Jahn-Teller效应使Cu(Ⅱ)的配合物的结构为一伸长的八面体;3个配合物的配位原子均为4个水分子的氧原子和两个异烟酸根的氮原子,羧基仅参与形成氢键。对配合物的热稳定性进行了研究,并对Cd(Ⅱ)配合物非等温热分解动力学方程和动力学参数进行了拟合,结果表明动力学补偿效应方程与数据拟合方法无关。     

快速升温结合温度控制——通向石墨炉恒温原子化的有效途径

众所周知,在恒温条件下的原子化,吸收信号峰值Ap可用下式表示: (1) 如果原子化温度T_p较高,原子生成速率常数K_1大大地大于原子散失速率常数K_2,在这种情况下,A_p≈βN_o,即达到了所谓理想原子化。但是。绝大多数的电热原子化器是在升温条件下工作的。如果在原子化过程中,石墨管的温度和时间成线性关系,即T_p=T_o+at_p,并且采用温度控制,那末,A_p可用公式(2)表示: (2) 把t_p=t′+t′代入公式(2)得: 如果t→0,则t′→0,A_p可近似表达为(2) 这里A_I为恒温条件下(原子化温度为T_p)的原子化峰值。     

原子质心运动和场模结构对场相位动力学的影响

运用Ｐｉｇｇ－Ｂａｒｎｅｔｔ的厄米相位公式,研究了Ｊ－Ｃ模型中原子质心运动和场模结构对场相位动力学的影响。在未考虑原子质心动力和考虑原子质心运动两种情况下,分别给出了场相位概率分布和相位涨落随时间的变化规律,并比较了两种情况下的场相位动力学,结果表明：原子质心动力导致场相位动力学的周期性演化,场模结构参数决定其周期的大小。     

电热原子吸收光谱分析中的等温原子化

本文评述了原子吸收光谱分析中等温原子化的实验技术和基本过程研究的动力学与热力学方法，并就基当前存在的问题进行了简要的讨论，收集文献４５篇。     

原子尺寸对Lennard-Jones液体玻璃转变过程中动力学不均匀性的影响

采用分子动力学模拟技术,通过对非高斯参数α_2(t)、粘度η等动力学参数的计算探究了原子尺寸对Lennard-Jones(LJ)液体在玻璃转变过程中动力学不均匀性的影响.结果表明在玻璃转变温度T_g附近,原子尺寸越小,粘度值增加越显著,且粘度随温度的变化满足Vogel–Fulcher–Tammann (VFT)方程;β弛豫阶段的非高斯参数α_2(t)与时间的关系满足幂律函数,且随着原子尺寸的减小动力学不均匀性越来越明显.     

V—舟石墨炉中原子化效率的测定

本文基于石墨炉中吸光度正比于原子吸收层的有效长度导出原子化效率的计算公式，基于两种方法求得的原子停留时间，计算了两种原子化效率（β１和β２）它们给出了在原子化阶段进入分析区分析原子总数的分数，测量了Ｖ－舟石墨炉内Ｇａ和Ｔ１在不同原子化温度时β１和β２值，讨论了原子蒸气消失过程对原子化效率的影响。     

共面双对称几何条件下电子碰撞Na原子单电离的三重微分截面

应用参数化的最佳有效势方法, 推广三体库仑波模型(3C)及动力学屏蔽的三体库仑波模型(DS3C模型)于Na原子, 计算了共面双对称几何条件下, 电子碰撞Na原子单电离的三重微分截面(TDCS), 与最近Murray的测量数据、Hitawala等人的扭曲波近似(DWBA)及考虑极化 的扭曲波近似(DWBAP)的理论结果进行了比较. 发现, DWBA在低入射能量反映了实验结果, 而3C计算在低入射能量时失效, DS3C计算对其有所改善. 入射能量较高时DS3C及3C结果的角度分布优于DWBA, 能够较好地定性描述上述碰撞过程. 说明对于共面双对称几何条件下的电子碰撞多电子原子单电离过程, 出射道三粒子间的动力学关联效应是比较强的.     

量子参数激励单摆的局域效应研究

分析了二能级原子在振幅调制主波场中动量扩散模型。这是一个量子参数激励单摆系统。这个量子系统在经典极限下表现混沌行为。在相同参数条件下,这个系统具有动力学特征。     

Model for the analytical signal in atomic absorption spectrometry with electrothermal atomization

A method for verification of analytical measurements in electrothermal atomic absorption spectrometry using a phenomenological model for physicochemical atomization processes is discussed. The influence of the sample matrix on basic kinetic parameters of atomization such as the analyte free-atom formation energy and the atomization rate constant has been shown. The similarity of atomization kinetic parameters obtained by calibrating the spectrometer to those for samples under study can be used as a verification criterion for analysis. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 295–298, May–June, 2008.     

Kinetic Model of Entry of Free Atoms into an Electrothermal Atomizer

A kinetic phenomenological model of the processes of atomization for atomic-absorptional spectrometry with electrothermal atomization that is based on solution of a one-dimensional equation of diffusion with two independent sources is suggested. The model takes into account the processes occurring both on the surface of a graphite furnace and inside its wall. The proposed model is used for describing the electrothermal atomization of copper and zinc.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 241–246, March–April, 2005.     

Kinetic studies of antimony and selenium atomization processes including a chemical modifier during their determination by electrothermal atomic absorption spectrometry

We have studied antimony and selenium atomization processes including a chemical matrix modifier (palladium-containing activated carbon) during their determination by electrothermal atomic absorption spectrometry. We have developed and fine-tuned an experimental setup for determining the kinetic characteristics (activation energy and frequency factor) for element atomization processes from measurements in the initial section of the analytical signal. We provide a rationale for the most likely mechanism for the interactions that occur. The results of the kinetic studies of the atomization processes showed that the modifier we developed was highly effective, as a result of formation of a thermally stable condensed system C-Pd-A (where A is the analyte). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 530–534, July–August, 2006.     

Electrothermal atomization of a substance with fractional condensation of the element being determined on a probe

This paper describes a method of electrothermal atomization with a fractional condensation of the elements being determined on a refractory probe with the aim of decreasing the matrix influences on the atomic-absorption signal. In the course of primary atomization of the sample, the probe is placed over the dosing port of a tubular atomizer. The internal argon flow directs the vapor to the probe for the condensation of the elements being determined. The matrix vapors volatilize. Then the probe is inserted into the atomizer for evaporation of the elements and analytical signal recording. It has been shown that this technique makes it possible to decrease the influence of sodium chloride and potassium sulfate on the absorption of Ag, Cd, Pb, and Au by a factor of 50–20,000 as compared to the atomization from the atomizer wall. In the case of Au, this decrease is comparable to the level attained under the conventional conditions of a stabilized temperature furnace with a platform, a modifier, and a background corrector based on the Zeeman effect, while for the other elements its efficiency is 1.5–40 times higher.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 124–128, January–February, 2005.     

Kinetic Approach to the Interpretation of Analyte Losses During the Preatomization Thermal Treatment in Electrothermal Atomization Atomic Absorption Spectrometry

A method for evaluating E_a(loss), the apparent activation energy of the analyte loss process during the high-temperature thermal pretreatment stage in electrothermal atomization atomic absorption spectrometry (ETA-AAS) has been developed. The method is based on extracting information from the declining portion of thermal pretreatment curves (in this case presented as absorbance vs pyrolysis time at various fixed temperatures). Five volatile analytes (As, Pb, Sb, Se, and Sn) have been studied in the presence of tungsten chemical modifier (20 μg of W in H₂O₂).

The data on E_a (loss) have been utilized together with those obtained from treating the atomization peaks E_a and with literature data on known values of bond energies and enthalpies of certain chemical reactions. Possible mechanisms of analyte losses and atomization are discussed.     

Study of the profiles of atomic absorption lines in an electrothermal atomizer

Narrow atomic absorption lines of Ba, Cs, Mg, and Tl are recorded in an electrothermal atomizer with a graphite tube furnace by the intracavity laser spectroscopy method. The conditions of applicability of this laser absorption method for reducing the observed profiles of spectral lines to the true ones are found. Measurement of the integral absorption coefficient has made it possible to determine the absolute number of free atoms of each element in the analyte volume at the maximum of the absorption peak under optimum conditions of atomizer heating. The Voigt parameters are determined from the profiles of absorption lines. Institute of Molecular and Atomic Physics of the National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 27–33, January–February, 1998.     

Some Recent Developments in Twin-Fluid Atomization

The results of recent researches on twin-fluid atomization are briefly reviewed, with particular emphasis on the effects of air and liquid properties on mean drop size. It is stressed that no single equation for the mean drop sizes produced in twin-fluid atomization can satisfactorily correlate all the experimental data from any given atomizer. This is because for all types of atomizers the mechanism of liquid breakup changes from one basic mode to another with changes in atomizer operating conditions and/or liquid properties. These different modes of atomization exhibit different dependencies on atomizer dimensions and various physical properties such as liquid viscosity and air density. Equations for estimating the mean drop sizes produced in the various modes of twin-fluid atomization are presented and discussed.     

燃油粒度对两相PDE爆震波速的影响

两相爆震燃烧的研究近来取得了较大的进步,但是仍有很多问题需要解决,诸如燃油的喷射、雾化和蒸发,燃油和氧化剂的混合,两相可爆混合物的短距离起爆等等．本文利用激光喷雾粒度分析仪分别就直射喷嘴与气动喷嘴研究了汽油的雾化情况,随着汽油流量的增加,两种喷嘴的雾化变化趋势相反．结合汽油、空气PDE模型机多循环爆震试验,发现汽油的粒度对模型机的爆震波速有较大的影响,粒度减小,波速增大,同时波速具有循环效应．     

Model for verification of measurement results in electrothermal atomic absorption spectrometry

We present a practical application of a phenomenological model for physicochemical atomization processes in determining heavy metal content by electrothermal atomic absorption spectrometry. Comparison of the analysis results with the NAHRES-33 (IAEA/AL/079) certificate of composition confirms the feasibility of using the proposed procedure in analysis of lichen materials. As the criterion for the reliability of the analysis results, we take the closeness of the values for the sample atomization parameters to the atomization parameters of the calibration solutions obtained, using a model for the analytical signal. We demonstrate application of the proposed procedure using as an example monitoring of heavy-metal air pollution by the lichen indication method.