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1.
The procedure in use at our institute for the extraction of the desired element concentrations in a sample from the peak data
obtained by a spectrum analysis program, is described in detail. The method is based on the use of zinc as a single comparator
and takes into consideration primary activation products as well as their daughter isotopes. After assigning isotopes to spectrum
peaks on the basis of γ-ray energies, the list of possible isotopes is reduced to a list of present isotopes with their concentrations
using criteria based on half life, specificity and intensity of γ-rays. For elements not observed, detection limits are estimated.
The procedure has been used extensively during the last two years and has shown to produce reliable results. 相似文献
2.
An interactive program for the computation of an isotopic spectrum of assumed composition whose empirical formula can be represented either as a set of chemical elements or in terms of structural fragments (super-elements) is described. The core of the program is a table of all isotopes of 82 elements of the periodic table and super-elements whose list is decided on by the user. The exact mass of isotopic peaks is determined by the program either from the position of the maximum value of the peak abundance or from the position of its centroid. The spectrum printout may be in one of several formats. The interaction with the program is very useful for operators of mass spectrometers in enabling them to estimate and verify assumptions about the elemental composition of spectrum peak groups. 相似文献
3.
B. Fazekas G. Molnár T. Belgya L. Dabolczi A. Simonits 《Journal of Radioanalytical and Nuclear Chemistry》1997,215(2):271-277
In short time activation analysis prompt gamma-activation analysis and in high rate -ray spectroscopy in general, the shape parameters for peaks and back ground usually vary, rendering spectrum evaluation codes based on a fixed shape calibration unsuitable. An interactive version of the well-known, fully automatic -ray spectrum analysis code HYPERMET has been developed in C ++ for the IBM-PC. It runs under MS-DOS, in conventional memory, and can handle up to 16k-channel spectra, recorded with CANBERRA's System 100 and AccuSpec and with ORTEC's ACE plug-in MCA cards. A Windows-like graphics environment is provided with mouse controlled pull-down menus, pop-up windows and rubber band expansion. All basic features of HYPERMET such as fully automatic peak search, nonlinear fitting of multiplets with automatically adjusted Gaussian peak widths exponential tails and a complex background function have been retained. All details of the fitting procedure are recorded in a data base, hence any fitted region can be retrieved and modified interactively, even after a fully automatic spectrum evaluation. The program also provides an output peak list in SAMPO90 format for further processing. The latter format is widely used in a number of sample analysis programs such as KAYZERO a software package fork
0 standardization in neutron activation analysis. 相似文献
4.
A FORTRAN computer program for automatic neutron activation analysis is presented. The program locates and identifies peaks
in a gamma-ray spectrum, calculates peak areas and the concentrations of the elements of interest in the sample. This program
was specifically designed for the SLOWPOKE reactor, it uses a semi-absolute method and does not need standards or flux monitors.
The program was written so as to minimize the computation time, and a typical 4096-channel spectrum is processed in five seconds
by an IBM 360/75 computer. 相似文献
5.
Fully automatic assignment of small molecules' NMR spectra without relying on chemical shift predictions
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Andrés M. Castillo Andrés Bernal Luc Patiny Julien Wist 《Magnetic resonance in chemistry : MRC》2015,53(8):603-611
We present a method for the automatic assignment of small molecules' NMR spectra. The method includes an automatic and novel self‐consistent peak‐picking routine that validates NMR peaks in each spectrum against peaks in the same or other spectra that are due to the same resonances. The auto‐assignment routine used is based on branch‐and‐bound optimization and relies predominantly on integration and correlation data; chemical shift information may be included when available to fasten the search and shorten the list of viable assignments, but in most cases tested, it is not required in order to find the correct assignment. This automatic assignment method is implemented as a web‐based tool that runs without any user input other than the acquired spectra. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Zhang Yingying Bi Haijie Wu Bingwei Yuan Da Shi Yan Feng Xiandong 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(9):3723-3733
The NaI(Tl) detector has been an important research topic and application in the field of in situ marine radioactive automatic monitoring because of its advantages of low power consumption, low cost, and good efficiency. However, its energy resolution is not high enough. This paper investigated an analytical method: spectrum de-noising, background correction based on the SNIP operator, peak search based on the top-hat transform and peak fitting using Gaussian distribution. Simulation and gamma spectra measured from seawater showed that the established energy spectrum analysis method presents satisfactory automatic analytical ability for identification and quantitatively analysis.
相似文献7.
A simple method is proposed for the gas-chromatographic analysis of complex gas mixtures containing hydrogen isotopes; the method is based on the substantial difference in the thermal conductivity of these isotopes. The total peak of the isotopes is recorded in a chromatogram, and the calibration is performed by pure reference gases. The concentrations of impurity gases in the analyzed mixture and in reference samples for each of the hydrogen isotopes are determined simultaneously. The fractional concentrations of protium and deuterium are calculated by the equations involving the heights of the unresolved peaks of hydrogen isotopes in chromatograms and concentrations of impurity components. 相似文献
8.
Mohamed Soliman Nader M. A. Mohamed A. M. Osman A. M. Abdel-Monem 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(1):89-93
In order to measure and obtain reliable data about elements via measuring of short-lived isotopes in liquid samples using neutron activation analysis, experiments have been carried out using a flowing sample neutron activation analysis method. During this work the performance and reliability for the proposed method have been tested using synthetic multi elements liquid samples. The radionuclide, associated elements and their concentration level have been measured using a counting system with a fixed dead-time. An HPGe spectrometry system was used to determine the most important γ-ray energies and intensities of these isotopes. The obtained results demonstrated the reliability and accuracy (bias <5 % and zeta score <2) of the tested method for determination the elemental content of liquid samples. 相似文献
9.
S. Landsberger K. Jackman L. Welch 《Journal of Radioanalytical and Nuclear Chemistry》2005,264(1):235-237
Summary {\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\froman\fprq2\fcharset238{\*\fname Times New Roman;}Times New Roman CE;}}
\viewkind4\uc1\pard\f0\fs24 We have developed a method for analyzing neutron activated sample data by using Microsoft Excel as the analysis engine. A simple technique for inputting data is based on report files generated by Canberra’s Genie-2000 spectroscopy system but could be easily modified to support other vendors having report formats with consistent text placement. A batch program handles operating an automatic sample changer, acquiring the data, and analyzing the spectrum to create a report of the peak locations and net area. The entire report is then transferred to within an Excel spreadsheet as the source data for neutron activation analysis. Unique Excel templates have been designed, for example, to accommodate short-lived and long-lived isotopes. This process provides us with a largely integrated solution to NAA while providing the results in an industry standard spreadsheet format. This software is ideally suited for teaching and training purposes.
\par } 相似文献
10.
A novel technique for the determination of Pt and Au at low concentrations is described. The method involves /K/ X-ray spectrometry preceded by fast neutron activation of the stable isotopes of the elements of interest. A full appraisal of the technique is presented for the analysis of small powdered samples. The sensitivity was optimized by employing a detector that was particularly effective at energies below 150 keV. The investigation formed the basis of a feasibility study which was utilized to establish if the application could be developed for the routine off-line determination of Pt and Au. We show that the method does not necessarily depend on the sample matrix, and that it proves to be a strong rival to conventional activation analysis. 相似文献
11.
《International journal of mass spectrometry and ion processes》1995,141(2):171-186
A method for the automatic extraction of spectra from GC-MS data is described. The program localizes chromatographic peaks and provides a reconstructed spectrum of each compound. It is particularly designed for low-sampling conditions frequently encountered with efficient GC columns, requiring threshold methods rather than methods based on peak shape; automatic threshold adjustments on the mass chromatograms are thus performed at different stages of the process. A test of the program on two sets of experimental data revealed better performances than manual data treatment, particularly in the case of low signal-to-noise ratios. 相似文献
12.
X射线光电子能谱(XPS)在科学研究中被广泛应用于碳材料表面官能团识别和结构缺陷判定,对表面组成结构识别和性能调控具有重要指导意义。XPS数据分析主观性强、sp2杂化态对应C1s谱峰峰形不对称以及各化学态对应峰位差异相对较小等因素是导致碳材料XPS数据分析难度高的主要原因。本文通过对XPS分析碳材料现状总结了当前新型碳材料XPS数据分析方法的不足(主要包括■化学态对应C1s谱峰峰形不对称峰形、各化学态半峰宽拟合的随意化以及数据的主观化);并结合实际材料通过■化学态谱峰峰形参考化、半峰宽相对限定化以及多数据分析客观化对新型碳材料XPS数据方法进行进一步规范,为XPS应用于新型碳材料表面元素及化学态定量高分辨研究提供理论依据和技术保障。 相似文献
13.
H. A. Das M. Dejkumhang H. J. Van Nieuwkerk J. J. Peeters 《Journal of Radioanalytical and Nuclear Chemistry》1983,77(1):223-233
The precision and accuracy of the peak energy allocation in γ-ray spectrometry govern the subsequent computer processing of
the data. By applying the main procedures for peak energy determination to a well-defined case, it is possible to define the
minimal statistical uncertainties to be expected. The systematic bias of the energies obtained is caused mainly by changes
in the total count rate. A correction can be applied based on the pulser peak. From the precision and the accuracy of the
peak energy determination, the scanning width for automatic peak indexing follows. 相似文献
14.
A tabulation of about 2000 precise gamma-ray energies of about 250 isotopes formed through neutron activation has been used
for the computer-assisted identification of the individual gamma emitters in complex gamma spectra. The identification consists
in the calculation of the gamma-ray energies from the peak maximum position by taking into account the deviation from linearity
of the spectrometer. Successive comparison of these energies with the energies of the tabulation allows then identification.
The identification procedure was tested on a number of samples of varying complexity and satisfactory results were obtained. 相似文献
15.
A pulsed monoenergetic 7Li+ ion beam (lab. energy 10–40 eV) is scattered from a highly collimated (= 1.5°) H2 nozzle beam. The time-of-flight spectrum of the ions scattered in the forward laboratory direction shows both a fast peak corresponding to forward center-of-mass scattering and a slow peak corresponding to wide-angle center-of-mass scattering. These peaks have been further resolved to show contributions from individual vibrational quantum transitions. From an analysis of the time-of flight spectra the differential inelastic cross sections for a wide range of angles and energies between 2 eV <Ecm < 9 eV have been determined. The spectra also contain information on rotational inelastic cross sections. 相似文献
16.
J. J. LaBrecque P. A. Rosales W. C. Parker 《Journal of Radioanalytical and Nuclear Chemistry》1983,78(1):87-99
In this work we shall discuss the preliminary results of employing eleven different radionuclides for elemental X-ray analysis
using a new analytical technique. This new technique mixes the radioisotope directly with the sample and this source sample
is directly placed on the detector window which is protected by a thin plastic film from contamination. An equal atomic mixture
of eight elements (Ti, Mn, Zn, Br, Zr, Ag, Sn and Ag) was prepared and doped separately with the eleven different isotopes
(Pm-147, S-35, Ni-63, Na-22, Co-137, Co-57, Cd-109, I-125, Am-241, Zn-65 and Fe-55). The spectrum of each is shown herein
with a discussion of the background, signal to noise ratio, corrected peak intensities, etc. Finally, the possible future
applications of this technique with some of the isotopes are presented. 相似文献
17.
Yu. N. Bourmistenko I. N. Ivanov V. V. Sviridova Yu. V. Feoktistov 《Journal of Radioanalytical and Nuclear Chemistry》1977,40(1-2):147-153
The possibilities of using a computer to optimize the conditions of gamma-activation analysis are considered. Criteria of
optimum conditions are formulated. The optimization program is constructed of the following operations being automatically
performed: (1) determination of a list of isotopes and their gamma-lines formed during the interaction between the activating
bremsstrahlung and the substance whose elemental composition elements to be analyzed plus matrix is preliminarily given; (2)
optimization of the analysis time regimes and the value of the maximum energy of the activating bremsstrahlung; (3) choice
of a gamma-line of the isotope of an element to be analyzed by which the quantitative determination of this element is expedient.
For these purposes a catalogue of nuclear-physical constants (half-lives and energies which was compiled from published data
tables of gamma-line outputs obtained experimentally under standardized conditions for different values of the maximum energy
of the bremsstrahlung as well as mathematical models of the monoenergetic gamma-ray spectra) has been used. 相似文献
18.
19.
G. P. Westphal F. Grass H. Lemmel J. Sterba P. Schröder Ch. Bloch 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(1):145-150
Automatic activation analysis (AAA) is rendered possible by a unique neutron activation analysis facility for short-lived
isomeric transitions based on a fast rabbit system with sample changer and sample separation, and an adaptive digital gamma-spectrometer
for very high counting rates of up to 106 cps. The system is controlled by a computer program performing irradiation control, neutron flux monitoring, and gamma-spectrometry
with real-time correction of counting losses, spectra evaluation, nuclide identification and calculation of concentrations
in a fully automatic procedure. As spectrometry is done by means of hundreds of sequentially measured pairs of concurrently
recorded loss-corrected and non-corrected spectra, concentrations are derived from an optimally weighted average of all individual
occurrences in this sequence of spectra which also enable the separation of isomeric transitions with coinciding energies
but different half-lives such as 116m2In (162.4 keV, T
1/2 = 2.2 s) and 77mSe (162.2 keV, T
1/2 = 17.4 s). To clear up repeatedly voiced misconceptions concerning the errors of loss-free counting our findings of 1978
and 1981 are reiterated, namely that the counting error of a peak in a corrected spectrum may be derived consistently from
the error of the same peak in the respective non-corrected spectrum and from the error of weighting factors in the corresponding
region of interest, according to the principle of propagation of errors. Experimental proof is provided for conditions of
stationary as well as rapidly varying counting rates and spectral shapes.
To the memory of Vincent P. Guinn. 相似文献
20.
González-Sánchez L Gómez-Carrasco S Aguado A Paniagua M Hernández ML Alvariño JM Roncero O 《The Journal of chemical physics》2004,121(1):309-320
In this work a simulation of the OHF(-) photodetachment spectrum is performed in a three-dimensional potential energy surface recently developed for OHF((3)A(")). The ground (2)A(') state potential of the anion is calculated in three dimensions based on accurate ab initio calculations and the reaction dynamics is studied using a wave packet method. The calculated spectrum shows a sequence of bands associated to vibrational HF(v) up to v=3. Each band is formed by a continuous spectrum and resonant structures. These resonances are associated to the OH-F channel well of the (3)A(") PES, in which fragmentation occurs through vibrational predissociation. Above the OH(v=0) threshold a new resonant pattern appears corresponding to heavy-light-heavy resonances. Special attention is paid to the assignment of these resonances because they mediate the reaction dynamics in the OH+F collision at low kinetic energies. The sequence of bands is in rather good agreement with that appearing in the experimental spectrum, especially at higher electron kinetic energies. At low kinetic energies, however, some other electronic states may contribute. The resonance structures might be washed out by the rotational average and the relatively low energy resolution of the experiment. 相似文献