共查询到18条相似文献,搜索用时 156 毫秒
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本文提出了一种测定锌的亚稳态能量转移发射光谱法。以氮气为工作气体,利用微波放电产生活化氮余辉,采用电热蒸发微量进样装置进样。考察了各实验参数对测定锌的影响,在472.2nm处测定锌,检出限为2.3ng。对实际样品中锌的测定取得了令人满意的结果。并讨论了氧对活化氮余辉的影响。 相似文献
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本文建立了一种简单的气相色谱法-常压微波等离子体发射光谱法联用实验装置。等离子体用自制的Surfatron获得。研究了等离子体操作参数对该装置分析特性的影响,证明该装置可用于某些含磷有机化合物的C/P比值的测定。 相似文献
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氢化物发生辅助雾化火焰原子吸收法测定水中铅 总被引:3,自引:0,他引:3
研究了一种提高火焰原子吸收测定铅灵敏度的新方法——氢化物发生辅助雾化的火焰原子吸收法;方法采用硼氢化钠与铅(Ⅳ)在原火焰原子吸收雾化器喷口处反应生成氢化物,以提高火焰原子吸收法的雾化效率;采用重铬酸钾一酒石酸预处理体系,重铬酸钾氧化样品中铅(Ⅱ)为铅(Ⅳ),酒石酸稳定铅(Ⅳ)的亚稳态化合物;对各种实验参数和干扰情况也进行了研究;方法操作简单、快速,灵敏度比通常的火焰原子吸收法提高了6.8倍;检出限(K=3,n=11)为6.64μg/L,线性范围为0.021~3.2mg/L;测定水样的回收率达94%~99%。 相似文献
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本文分别用亚甲基和甾体雌二醇刚性链将吲哚与9,10-二甲氧基蒽连接起来,合成了两个分子内能量转移体系,研究了分子內吲哚的激发能向9,10-二甲氧基蒽的传递过程与距离及溶剂环境的关系;发现在两个体系中激发吲哚都可以发生从吲哚到9,10-二甲氧基蒽的单重态-单重态能量转移,在远距离的条件下,能量转移按偶极子-偶极子共振机制进行,由实验结果,根据Forster公式计算得到的给体与受体之间的距离与用分子模型测量得到的距离是一样的,并研究了溶剂极性对能量转移过程的影响。 相似文献
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Tang Xiaoshuan Wang Hongmei Han Haiyan Li Jianquan Jin Shunping Huang Guodong Chu Yannan Zhang Weijun Zhou Shikang 《化学物理学报(中文版)》2005,18(6):887-891
A new method for producing electronically excited nitrogen monohalides NX(b) (X=F,Cl,Br) is reported. The strong emission spectra of NBr(b1Σ+→X3Σ–) are observed when alkyl bromides (CHBr3, CH2Br2, C2H5Br, and C4H9Br) are added to a stream of active nitrogen, generated by a hollow-cathode discharge of N2, in a flowing afterglow system. Some tentative experiments show that the electronically excited NBr(b) is formed by means of metastable N2(A3Σu+) Electronic-to-Electronic energy transfer to NBr(X), which is from the reaction of N(4S) with alkyl bromides. The emission spectra of NCl(b1Σ+→X3Σ–) are obtained when CCl4 or SOCl2 is admitted into a flow of active nitrogen, but neither CHCl3 nor CH2Cl2 addition results in such an emission. It has been proposed that the origin of the excited NCl(b) is an energy transfer from N2 (A) to NCl(X), generated by the reaction of N(4S) with CCl3 (or SOCl2). Similar experiments are also carried out with SF6 as reagent of active nitrogen, or as mixture with N2 in the discharge. By recording fluorescence it was found that excited NF(b) is produced only under discharge through N2/SF6 mixture. The NF(b) state presumably arises from the energy transfer from N2(A) to NF(X), and the latter is generated from the abstraction of fluorine by N(4S) from SF5. 相似文献
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Ali M. Ghazzawi George E. Venikouas Richard C. Powell 《Journal of solid state chemistry》1985,57(3):332-337
Time-resolved spectroscopy after pulsed nitrogen laser excitation was used to characterize the energy transfer between Eu2+ ions in different crystal field sites in RbMgF3 crystals. The results are consistent with electric dipole—dipole interaction and indicate that the Eu2+ ions are forming clusters in this host. As temperature is raised, the upper crystal field components of the metastable states of the ions become thermally populated and this changes the characteristics of the transfer process. 相似文献
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R. G. Cooks J. H. Beynon M. Bertrand M. K. Hoffman 《Journal of mass spectrometry : JMS》1973,7(11):1303-1312
The use of kinetic energy release measurements in the structural characterization of ions formed in the mass spectrometer and in the determination of fragmentation mechanisms is demonstrated. In combination with information on the mode of energy partitioning in some of these reactions this allows the following conclusions: (i) The metastable [C7H8]8˙ ions formed from toluene, cyclohepatatriene, n-butylbenzene, the three methyl anisoles, methyl tropyl ether and benzyl methyl ether all undergo loss of H˙ from a common structure. (ii) The metastable [C7H7]+ ions generated from the same sources and from benzyl bromide, benzyl alcohol, p-xylene and ethylbenzene appear to undergo loss of acetylene from both the benzylic and the tropylium structures. (iii) The metastable [C7H7OCH3]+˙ ether molecular ions undergo loss of CH3˙ by two types of mechanism, simple cleavage to give the aryloxy cation (not observed for benzyl methyl ether) and a rearrangement process which appears to lead to protonated tropone as the product. (iv) Loss of formaldehyde from the metastable [C7H7OCH3]+˙ molecular ions involves hydrogen transfer via competitive 4- and 5-membered cyclic transition states in the case of the anisoles and in the case of methyl tropyl ether, while for benzyl methyl ether, hydrogen transfer in the nonisomerized molecular ion occurs via a 4-membered cyclic transition state to yield the cycloheptatriene molecular ion. 相似文献
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Measurements have been made of the vibrational branching ratio (υ′=0)/(υ′=1) in N*2 (C3Πu) formed in electronic energy transfer collisions between argon metastable atoms and ground state nitrogen molecules, using crossed molecular beams. In the relative collision energy range, 0.08–0.20 eV, this ratio is 3.5±0.2. 相似文献
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Bernt Koschuh Maria Montes Jose Francisco Camuña Rosario Pereiro Alfredo Sanz-Medel 《Mikrochimica acta》1998,129(3-4):217-223
The element specific detection of the adsorbable organic halogen (AOX) parameter in waters has been investigated by adsorption of the halogenated analytes on activated carbon, incineration to yield carbon dioxide and hydrogen halide, trapping of the halide on a 0.01 M sodium hydroxide solution and online introduction of the halogen formed by continuous oxidation into a microwave induced plasma (MIP). Detection has been carried out by optical emission spectrometry (OES) in the visible spectral region.The performance of three microwave cavities for MIP-OES running at atmospheric pressure (Beenakker, Surfatron and Microwave Plasma Torch) as well as a reduced pressure Surfatron were investigated for halide analysis. The Surfatron device operated at 30 torr provided the best detection limits: 3ng.ml–1 for chloride and 8 ng.ml–1 for bromide; consequently, it was the plasma chosen for AOX analysis.On-line continuous oxidation of organic compounds using KMnO4 in H2SO4 medium and in batch catalytic dechlorination with a Fe/Pd system were investigated as alternatives to the incineration method for the destruction of organic halogens to render inorganic halides are also investigated.Finally, the optimized method has been applied successfully to the determination of organochloride and organobromide in spiked river waters, being the recoveries in the interval 92–105%. 相似文献
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Van den Bergh V Vanhees I De Boer R Compernolle F Vinckier C 《Journal of chromatography. A》2000,896(1-2):135-148
In this paper an identification method is described for determining the degradation products of the reaction of alpha-pinene with hydroxyl radicals. The study is carried out in a fast-flow reactor equipped with a specially designed microwave cavity (type Surfatron) allowing to operate at pressures up to 100 Torr (1 Torr=133.322 Pa). The semivolatile products are collected on a liquid nitrogen trap (LN2 trap) and the batch samples are subsequently analysed by GC-MS and HPLC-MS. Some samples were also collected directly on a LpDNPH-cartridge, followed by HPLC-MS analysis. When experiments were carried out at 50 Torr both GC-MS and HPLC-MS measurements showed that campholenealdehyde and pinonaldehyde were identified as condensable oxidation products for the alpha-pinene/OH reaction, with pinonaldehyde being the main product. Furthermore, the LN2 trap collection method based on the in situ conversion of aldehydes and ketones to their 2,4-dinitrophenylhydrazone derivatives allowed the determination of formaldehyde, acetaldehyde and acetone. Although formaldehyde and acetone are present in small amounts in blank samples it could be established that formaldehyde and acetone are also formed in the alpha-pinene/OH reaction. 相似文献
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E. G. Jones L. E. Bauman J. H. Beynon R. G. Cooks 《Journal of mass spectrometry : JMS》1973,7(2):185-192
The kinetic energy released in unimolecular reactions, as measured from the width of the corresponding metastable peak, shows only a small dependence on such parameters as source temperature, ion-source residence time and ion acceleration voltage. Similarly, fragmenting ions generated from different members of an homologous series of molecular ions have been found to release the same kinetic energy and hence do not exhibit a degrees-of-freedom effect analogous to that for metastable abundances. In general, molecular ions formed by electron-impact have been found to release slightly less kinetic energy on fragmentation than the corresponding ions formed via a fragmentation sequence. These observations suggest that kinetic energy release is a useful method of structural characterization of metastable ions; while increase in the average internal energies of the ions sample lead to larger energy releases, this effect is usually small. The use of a very narrow energy resolving (β) slit and a procedure in which the metastable peak width is extrapolated to zero slit width has been found to improve the accuracy of measurement of the kinetic energy release, particularly when the metastable and main beam peak widths are of comparable magnitude. 相似文献