International Journal of Mass Spectrometry and Ion Physics最新文献_第8页

Selective ion source for trace gas analysis 痕量气体分析的选择性离子源

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85006-2

W. Genuit, Chen He-Neng , A.J.H. Boerboom, J. Los

引用次数: 10

Approximate determination of absolute unimolecular rate constants using the field ionization kinetic method 用场电离动力学方法近似测定绝对单分子速率常数

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85002-5

Willi A. Brand, K. Levsen

{"title":"Approximate determination of absolute unimolecular rate constants using the field ionization kinetic method","authors":"Willi A. Brand, K. Levsen","doi":"10.1016/0020-7381(83)85002-5","DOIUrl":"10.1016/0020-7381(83)85002-5","url":null,"abstract":"<div>A method is described which allows the determination of absolute unimolecular rate constants from ion lifetime measurements using the field ionization technique. For this purpose the molecules are heated to ∼ 800 K prior to ionization by a high electric field. The internal energy distribution of the molecular ions generated in this way is mainly determined by the thermal energy distribution which can be calculated with fair accuracy. The additional small amount of energy transferred during the ionization process can be estimated by comparing the experimental and calculated temperature dependence of the molecular ion. If ions energized in this manner undergo a unimolecular decomposition, the rate of formation of a given fragment can be determined in the time range 10−11-10−5 s after ionization. Knowledge of the internal energy distribution of the precursor and the rate of formation allows the determination of the rate constant as a function of the internal energy. The accuracy of this method is limited by uncertainty in the determination of the energy distribution and the potential distribution in the source. Approximate rate constants are reported for methyl loss from ionized t-butylbenzene and diethylether in the range 104-109 s−1. Reasonable agreement with RRKM calculations and—as far as available—with photo-electron-photoion coincidence measurements is achieved. It is demonstrated that the method allows the determination of very steep k(E) functions, which do not lend themselves to other methods.</div>","PeriodicalId":13998,"journal":{"name":"International Journal of Mass Spectrometry and Ion Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1983-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0020-7381(83)85002-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86096656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Multiphoton laser ionization mass spectrometry of cesium iodide and atomic iodine 碘化铯和原子碘的多光子激光电离质谱分析

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85003-7

M. Balooch, D.R. Olander

引用次数: 5

Häufigkeitsverteilungen von einfach und doppelt positiv geladenen molekülionen ausgewählter chemischer elemente im funkenplasma 每个产生简单和双正面化学成分的分子的普遍分布

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85016-5

S. Becker, H.-J. Dietze

{"title":"Häufigkeitsverteilungen von einfach und doppelt positiv geladenen molekülionen ausgewählter chemischer elemente im funkenplasma","authors":"S. Becker, H.-J. Dietze","doi":"10.1016/0020-7381(83)85016-5","DOIUrl":"10.1016/0020-7381(83)85016-5","url":null,"abstract":"<div>The knowledge of the abundance distribution and intensities of molecular ions has been of special interest for mass spectrographic trace analysis. A double-focussing mass spectrograph has been used to measure the intensities of carbide, oxide and dimer cluster ions for the IVa, IIIb and VIb elements, iron, nickel, silver, tantalum, bismuth and uranium. For some elements a typical alternating abundance distribution of carbide ions, MCn+, was found which is comparable with the distribution of carbon cluster ions in a high temperature plasma.Whereas singly-charged molecular ions with relative abundances of ⩽ 10−2 were observed the doubly-charged molecular ions could be measured to the order of magnitude of ⩽ 10−4.Triply-charged molecular ions of the investigated elements were not formed in the mass spectra (detection limits ⩾ 10−10). We can conclude that either triply-charged molecular ions are not formed in a high temperature plasma or that their lifetime is lowered with the time-of-flight through the mass spectroscopic system.</div>","PeriodicalId":13998,"journal":{"name":"International Journal of Mass Spectrometry and Ion Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1983-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0020-7381(83)85016-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74489673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 25

Fractionation in the thermal ionization source 热电离源中的分馏

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85004-9

K. Habfast

{"title":"Fractionation in the thermal ionization source","authors":"K. Habfast","doi":"10.1016/0020-7381(83)85004-9","DOIUrl":"10.1016/0020-7381(83)85004-9","url":null,"abstract":"<div>In this paper a model for isotopic fractionation in the thermal ionization source is presented. The samples, normally loaded as salts, are assumed to evaporate, in general, as binary vapors of two chemically different forms. The molecular species in the vapor might either dissociate before ionization and the metal might then be ionized; or, alternatively, molecular ions might be generated which then dissociate into metal ions. Whereas isotopic effects during ionization are negligible, such effects have to be considered for the dissociation process.The dependence of the observed isotope ratio on the chemical form of the loaded sample and on the temperature of the ionization can be explained with this model, whereas the time dependence and the effects of reverse or enhanced fractionation of the observed isotope ratio are readily explained by a generalized Rayleigh distillation equation.The application of the fraetionation model to the normalization of observed isotope ratios to an internal standard ratio shows the principal limits for the accuracy of normalization. The commonly used normalization techniques and their inherent errors are considered in the light of the fractionation model and an improved normalization formula is presented which uses the concept of the “apparent mass”. Finally, the model is used to propose experimental methods for the accurate determination of non-normalizable isotopic ratios.</div>","PeriodicalId":13998,"journal":{"name":"International Journal of Mass Spectrometry and Ion Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1983-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0020-7381(83)85004-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89114489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 50

Energy dependence of the fragmentation of the n-butylbenzene molecular ion 正丁基苯分子离子断裂的能量依赖性

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85018-9

Alex G. Harrison, Margaret S. Lin

引用次数: 45

Analysis of doubly-charged ion reactions and consecutive two-step degradation processes by means of metastable peak mapping 用亚稳峰映射法分析双电荷离子反应和连续两步降解过程

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85010-4

A. Fraefel, J. Seibl

引用次数: 4

The mass spectra of crown ethers: The effects of preferred secondary structures on fragmentation patterns 冠醚的质谱:优选二级结构对裂解模式的影响

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85012-8

Y.C. Lee, Alexander I. Popov, John Allison

引用次数: 25

Enhanced ionization of organic salts in secondary-ion mass spectrometry 二级离子质谱法中有机盐的强化电离

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85008-6

B.H. Hsu, Y.-X. Xie, K.L. Busch, R.G. Cooks

{"title":"Enhanced ionization of organic salts in secondary-ion mass spectrometry","authors":"B.H. Hsu, Y.-X. Xie, K.L. Busch, R.G. Cooks","doi":"10.1016/0020-7381(83)85008-6","DOIUrl":"10.1016/0020-7381(83)85008-6","url":null,"abstract":"<div>Ammonium chloride increases the absolute signal intensity for the intact cations of organic ammonium, pyrylium and phosphonium salts when admixed in 10−103-fold excess. This signal enhancement results in improved signal-to-noise ratios and is achieved without addition of extraneous ions to the spectrum. The ionization efficiency (secondary ions produced per incident primary ion) is similar for neat and ammonium chloride diluted samples. However, the ionization yield (secondary ions produced per sample molecule) is enhanced by the matrix by four orders of magnitude. Sensitivity, calculated here for a desorption ionization method, is 0.5−1 × 10−10 C μg−1, and is less than that of electron ionization and chemical ionization sources. Spectra of submicrogram amounts of organic species in ammonium chloride are stable and can be recorded continuously for many hours, as compared to less than an hour for the neat compounds. Even subnanogram amounts of sample diluted in ammonium chloride give spectra which last a number of minutes. Matrix-diluted samples may be withdrawn from the spectrometer and stored for days before being reanalyzed without incident. With this matrix, the technique is essentially nondestructive. Total ionization yields for matrix-diluted samples are estimated at 0.01-0.1%. Primary-ion fluxes impinging on matrix-diluted samples exceed static SIMS limits without evidence of beam damage.</div>","PeriodicalId":13998,"journal":{"name":"International Journal of Mass Spectrometry and Ion Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1983-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0020-7381(83)85008-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85027048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 26

Mass-spectrometric determination of enthalpies of dissociation of gaseous complex fluorides into neutral and charged particles. VII. MF-ThF4 systems (M = Li, Na, K, Rb, Cs) 气态络合氟化物解离成中性和带电粒子的焓的质谱测定。7MF-ThF4体系(M = Li, Na, K, Rb, Cs)

International Journal of Mass Spectrometry and Ion Physics Pub Date : 1983-07-01 DOI: 10.1016/0020-7381(83)85014-1

L.N. Sidorov, L.V. Zhuravleva, M.V. Varkov, E.V. Skokan, I.D. Sorokin, Yu.M. Korenev, P.A. Akishin

{"title":"Mass-spectrometric determination of enthalpies of dissociation of gaseous complex fluorides into neutral and charged particles. VII. MF-ThF4 systems (M = Li, Na, K, Rb, Cs)","authors":"L.N. Sidorov, L.V. Zhuravleva, M.V. Varkov, E.V. Skokan, I.D. Sorokin, Yu.M. Korenev, P.A. Akishin","doi":"10.1016/0020-7381(83)85014-1","DOIUrl":"10.1016/0020-7381(83)85014-1","url":null,"abstract":"<div>The effusion method together with mass spectral analysis is used to study ion/molecule equilibria, involving the ThF5− ion, and equilibria between neutral species, involving NaThF5 molecules. The experimental data obtained made it possible to calculate the enthalpies of formation of ThF5−: <ul><li>1.Δ H298,f0, (ThF5−) = −2432.4 ±12.5 kJ mol−1 and NaThF5:</li><li>2.ΔH298,f0 (NaThF5) = −2339.7 ±13.8 kJ mol−1 and estimate the following enthalpies:</li><li>3.ΔH298,f0 (LiThF5) = −2373.2±18.0 kJ mol −1 li]ΔH298,f0 (KThF5) = −2381.5±15.5 kJ mol−1</li><li>4.ΔH298,f0 (RbThF5) = −2393.2 ±20.9 kJ mol−1</li><li>5.ΔH298,f0 (CsThF5) = −2393.7 ±17.2 kJ mol−1</li></ul> Activities in the system NaF-ThF4 were determined and estimated in the systems MF-ThF4, where M = Li, K, Rb or Cs. The equations are given for calculating the activities at temperatures from 800 to 1300 K.</div>","PeriodicalId":13998,"journal":{"name":"International Journal of Mass Spectrometry and Ion Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1983-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0020-7381(83)85014-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73838388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6