Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry最新文献

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Heat Capacities of Polyethylene IV. High Molecular Weight Linear Polyethylene. 聚乙烯的热容量 IV.高分子量线性聚乙烯
Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry Pub Date : 1976-01-01 Epub Date: 1976-02-01 DOI: 10.6028/jres.080A.009
Shu-Sing Chang
{"title":"Heat Capacities of Polyethylene IV. High Molecular Weight Linear Polyethylene.","authors":"Shu-Sing Chang","doi":"10.6028/jres.080A.009","DOIUrl":"10.6028/jres.080A.009","url":null,"abstract":"<p><p>A high molecular weight linear polyethylene sample has been studied by adiabatic calorimetry from 10 to 380 K. Two broad temperature regions of unusual spontaneous temperature drift have been observed. The phenomena occurring around 240 K are similar to that observed in other polyethylene samples studied in this series, and are presumed to be caused by the relaxational processes in the amorphous phase. The weak exothermic behavior occurring around 160 K is presumed to be caused by the stabilization of the quenched sample.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"80A 1","pages":"51-57"},"PeriodicalIF":0.0,"publicationDate":"1976-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291314/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37757622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Line Strengths and Lifetimes of Levels in Neutral Uranium. 中性铀水平的线强度和寿命。
Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry Pub Date : 1976-01-01 Epub Date: 1976-02-01 DOI: 10.6028/jres.080A.002
Charles H Corliss
{"title":"Line Strengths and Lifetimes of Levels in Neutral Uranium.","authors":"Charles H Corliss","doi":"10.6028/jres.080A.002","DOIUrl":"https://doi.org/10.6028/jres.080A.002","url":null,"abstract":"<p><p>Relative intensities of 549 U I lines observed in a dc copper arc are used to derive transition probabilities and oscillator strengths. Upper limits to lifetimes for 65 levels in neutral uranium atoms are determined.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"80A 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"1976-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291310/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37757617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 41
Computer Simulation of Metastable Fluid States in the Lennard-Jones System. Lennard-Jones系统亚稳流体状态的计算机模拟。
Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry Pub Date : 1976-01-01 Epub Date: 1976-02-01 DOI: 10.6028/jres.080A.011
Harold J Raveché, William B Streett
{"title":"Computer Simulation of Metastable Fluid States in the Lennard-Jones System.","authors":"Harold J Raveché,&nbsp;William B Streett","doi":"10.6028/jres.080A.011","DOIUrl":"https://doi.org/10.6028/jres.080A.011","url":null,"abstract":"<p><p>Using the Monte Carlo method in statistical mechanics, we have simulated high density metastable states. We find that nucleation from a three dimensional fluid array to a crystalline solid is possible, but that periodic boundary conditions and the small size of the system inhibit the formation of perfect crystals. Evidence for the existence of an amorphous solid state has also been observed, and the pair correlation function of this state exhibits some of the features associated with random close-packed arrays of hard spheres. The possible relation between these simulations and the formation of glassy states in real systems is briefly discussed.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"80A 1","pages":"59-64"},"PeriodicalIF":0.0,"publicationDate":"1976-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5291315/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37757623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 10
Homogeneous Nucleation in Polyethylene: Molecular Weight Dependence. 聚乙烯中的均匀成核:分子量依赖性。
Gaylon S Ross, Lois J Frolen
{"title":"Homogeneous Nucleation in Polyethylene: Molecular Weight Dependence.","authors":"Gaylon S Ross,&nbsp;Lois J Frolen","doi":"10.6028/jres.079A.027","DOIUrl":"10.6028/jres.079A.027","url":null,"abstract":"<p><p>The droplet technique was used to obtain estimates of the isothermal rate of homogeneous crystal nucleation in highly supercooled melts of 8 characterized fractions of linear polyethylene (weight average molecular weights from 3,100 to 249,000). The data obtained from these experiments were analyzed in accord with current theories of homogeneous nucleation of chain folded crystals. Values for the quantity σ<sup>2</sup>σ <sub><i>e</i></sub> , where <i>σ</i> and σ <sub><i>e</i></sub> are the lateral and end-surface free energies of the crystal, were estimated as a function of molecular weight. Sample 3.2 K was found to be anomalous in its nucleation behavior. When we assume that this sample crystallizes in the extended chain form and calculate σ<sup>3</sup> instead of <i>σ</i> <sup>2</sup> <i>σ</i> <sub><i>e</i></sub> the value for σ is found to be 10.57 ergs/cm<sup>2</sup> which is in reasonable agreement with the value 9.6 ergs/cm<sup>2</sup> found by other investigators for linear hydrocarbons. However, there remains the question as to whether sample 3.2 K ever underwent homogeneous nucleation. For samples 9.70, 11.74, and 23.0 K, σ<sup>2</sup>σ <sub><i>e</i></sub> was found to increase rapidly due to a decrease in the number of cilia per chain fold as the molecular weight increases. For higher molecular weights the value for σ<sup>2</sup>σ <sub><i>e</i></sub> levels off and the average value of σ<sup>2</sup>σ <sub><i>e</i></sub> for samples 23.0 to 249 K was found to be 19,000 ergs<sup>3</sup>/cm<sup>6</sup>. The experimental value of the absolute nucleation frequency <i>I</i> <sub>0</sub>, was found to differ from the theoretical value by approximately 1 × 10<sup>12</sup>. If one assumes that the surface free energies are temperature dependent [i.e., <math><mrow><mi>σ</mi> <mo>=</mo> <msub><mi>σ</mi> <mn>1</mn></msub> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mover><mi>x</mi> <mo>¯</mo></mover> <mtext>Δ</mtext> <mi>T</mi> <mo>)</mo></mrow> </math> and <math> <mrow><msub><mi>σ</mi> <mi>e</mi></msub> <mo>=</mo> <msub><mi>σ</mi> <mrow><mi>e</mi> <mn>1</mn></mrow> </msub> <mo>(</mo> <mn>1</mn> <mo>+</mo> <mover><mi>y</mi> <mo>¯</mo></mover> <mtext>Δ</mtext> <mi>T</mi> <mo>)</mo></mrow> </math> where <math> <mrow><mover><mi>x</mi> <mo>¯</mo></mover> <mo>=</mo> <mo>-</mo> <mn>0.0073</mn></mrow> </math> and <math> <mrow><mover><mi>y</mi> <mo>¯</mo></mover> <mo>=</mo> <mn>0.014</mn></mrow> </math> ] the average value of σ<sup>2</sup>σ <sub><i>e</i></sub> > changes only slightly (to 19,800 ergs<sup>3</sup>/cm<sup>6</sup>) due to the compensating effects in the signs of the temperature corrections and <i>I</i> <sub>0</sub> is close to the theoretical value, 1 × 10<sup>34</sup> nuclei/cm<sup>3</sup>/s.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"701-711"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589418/pdf/jres-79A-701.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37748202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 26
Absolute Isotopic Abundance Ratios and the Atomic Weight of a Reference Sample of Potassium. 钾参考样品的绝对同位素丰度比和原子量。
E L Garner, T J Murphy, J W Gramlich, P J Paulsen, I L Barnes
{"title":"Absolute Isotopic Abundance Ratios and the Atomic Weight of a Reference Sample of Potassium.","authors":"E L Garner,&nbsp;T J Murphy,&nbsp;J W Gramlich,&nbsp;P J Paulsen,&nbsp;I L Barnes","doi":"10.6028/jres.079A.028","DOIUrl":"10.6028/jres.079A.028","url":null,"abstract":"<p><p>Solid sample, thermal ionization, mass spectrometry has been used to obtain absolute values for the isotopic abundance ratios of a reference sample of potassium. Standards of known isotopic composition, prepared by gravimetrically mixing nearly isotopically and chemically pure separated isotopes of, <sup>39</sup>K and <sup>41</sup>K, were used for calibration. The absolute isotopic abundance ratios are : <sup>39</sup>K/<sup>41</sup>K = 13.8566 ± 0.0063 and <sup>40</sup>K/<sup>41</sup>K = 0.0017343 ± 0.0000061 which yield atom percent compositions of <sup>39</sup>K=93.2581 ± 0.0029. <sup>40</sup>K = 0.01167 ± 0.00004, and <sup>41</sup>K = 6.7302 ± 0.0029. The calculated atomic weight for potassium is 39.098304 ± 0.000058. The indicated uncertainties are overall limits of error which are the sum of the uncertainty components for ratio determinations and the components covering the effects of known sources of possible systematic error.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"713-725"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589417/pdf/jres-79A-713.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37748203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 68
Absolute Isotopic Abundance Ratios and the Atomic Weight of a Reference Sample of Silicon. 硅参考样品的绝对同位素丰度比和原子量。
I L Barnes, L J Moore, L A Machlan, T J Murphy, W R Shields
{"title":"Absolute Isotopic Abundance Ratios and the Atomic Weight of a Reference Sample of Silicon.","authors":"I L Barnes,&nbsp;L J Moore,&nbsp;L A Machlan,&nbsp;T J Murphy,&nbsp;W R Shields","doi":"10.6028/jres.079A.029","DOIUrl":"10.6028/jres.079A.029","url":null,"abstract":"<p><p>Absolute values have been obtained for the isotopic abundance ratios of a reference sample of silicon using electron impact mass spectrometry. Samples of known isotopic composition prepared from nearly isotopically pure separated silicon isotopes were used to calibrate the mass spectrometers. The resulting absolute <sup>28</sup>Si/<sup>30</sup>Si ratio=29.74320±0.00747 and the <sup>29</sup>Si/<sup>30</sup>Si ratio=1.50598±0.00086 which yield atom percents of <sup>28</sup>Si = 92.22933± 0.00155, <sup>29</sup>Si = 4.66982 ± 0.00124 and <sup>30</sup>Si = 3.10085 ± 0.00074. The atomic weight calculated from this isotopic composition is 28.085526 0.000056. The indicated uncertainties are overall limits of error based on 95 percent confidence limits for the means and allowances for the effects of known sources of possible systematic error. A study of natural <sup>28</sup>Si/<sup>30</sup>Si ratio variations reported in the literature extends the estimated uncertainty in the atomic weight of natural silicon to ±0.00039.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"727-735"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589419/pdf/jres-79A-727.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37748204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 13
Absolute Determination of the Electrochemical Equivalent and the Atomic Weight of Zinc I. Method, Apparatus, and Preliminary Experiments. 锌的电化学当量和原子量的绝对测定I.方法、仪器和初步实验。
George Marinenko, Robert T Foley
{"title":"Absolute Determination of the Electrochemical Equivalent and the Atomic Weight of Zinc I. Method, Apparatus, and Preliminary Experiments.","authors":"George Marinenko, Robert T Foley","doi":"10.6028/jres.079A.030","DOIUrl":"10.6028/jres.079A.030","url":null,"abstract":"<p><p>The use of a specially designed coulometer and a high accuracy coulometric circuit resulted in the accurate measurement of the electrochemical equivalent and atomic weight of zinc. The experimental conditions to make possible the final precise and accurate measurements were established. These include a study of mechanical losses from the anode during the electrolysis and the corrosion of zinc in various media used in the determination. The effects of both of these sources of error may be controlled. Mechanical losses are minimized when an amalgamated electrode is used; corrosion, when an amalgamated electrode is used in an air free system. An electrolyte, 25 wt. percent NH<sub>4</sub>Cl and 3 molal ZnCl<sub>2</sub>. was used in these determinations. This report presents the account of research which was prerequisite to subsequent accurate determination of the electrochemical equivalent and the atomic weight of zinc.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"737-745"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589413/pdf/jres-79A-737.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37747051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Use of Synchrotron Radiation as an Absolute Source of VUV Radiation. 同步辐射作为紫外辐射的绝对来源。
D L Ederer, E B Saloman, S C Ebner, R P Madden
{"title":"The Use of Synchrotron Radiation as an Absolute Source of VUV Radiation.","authors":"D L Ederer,&nbsp;E B Saloman,&nbsp;S C Ebner,&nbsp;R P Madden","doi":"10.6028/jres.079A.032","DOIUrl":"https://doi.org/10.6028/jres.079A.032","url":null,"abstract":"<p><p>Synchrotron radiation has been used as a standard source to calibrate spectrographic instruments at the National Bureau of Standards (NBS). Conceptually it is straightforward to apply the calculable continuum distribution of synchrotron radiation to problems requiring a source of known irradiance if the electron energy, the radius of the electron orbit, and the beam current are known. In practice many factors affect the accuracy of such a calibration, such as temporal and spatial variations in the electron beam, uncertainties in the orbital radius and maximum energy of the orbiting electron beam. These sources of error are discussed and the method of calibration on SURF-I is specified. A storage ring synchrotron radiation facility (SURF-II) is now operational at NBS. The calibration techniques developed for SURF-I are applied to SURF-II with anticipated improvements in calibration accuracy. For SURF-I the incident flux was determined with an accuracy of 15 percent while for SURF-II we anticipate accuracies of about 7 percent.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"761-774"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589412/pdf/jres-79A-761.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37747054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 33
Corrections to Paper Entitled "Third Virial Coefficient for Air-Water Vapor Mixtures". 对题为“空气-水蒸气混合物的第三维里系数”的论文的修正。
R W Hyland, E A Mason
{"title":"Corrections to Paper Entitled \"Third Virial Coefficient for Air-Water Vapor Mixtures\".","authors":"R W Hyland,&nbsp;E A Mason","doi":"10.6028/jres.079A.033","DOIUrl":"10.6028/jres.079A.033","url":null,"abstract":"<p><p>This note points out errors in the values of the third virial coefficients for pure water vapor which appeared in a 1967 paper by Hyland and Mason. The errors arose while converting from the units of Goff and of Keyes to the desired units of (liter/mole)<sup>2</sup>. The consequences of the errors are outlined, and it is shown that there is no effect on the primary results of the paper, namely, in the preferred values of the third interaction virial coefficient for air-water vapor mixtures, <i>C</i> <sub><i>aww</i></sub> .</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"775-776"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589416/pdf/jres-79A-775.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37747055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Absolute Determination of the Electrochemical Equivalent and the Atomic Weight of Zinc II. Final Determination. 锌的电化学当量和原子量的绝对测定Ⅱ。最终决定。
George Marinenko, Robert T Foley
{"title":"Absolute Determination of the Electrochemical Equivalent and the Atomic Weight of Zinc II. Final Determination.","authors":"George Marinenko,&nbsp;Robert T Foley","doi":"10.6028/jres.079A.031","DOIUrl":"10.6028/jres.079A.031","url":null,"abstract":"<p><p>A new, successful approach to the determination of atomic weights of suitable elements has been demonstrated in this research. An absolute constant-current coulometric method was employed for the determination of the electrochemical equivalent and the atomic weight of zinc. The effects of possible sources of systematic error were investigated and appropriate corrections applied. The newly determined values of the two constants are 0.3387958 mg C<sup>-1</sup> and 65.3771 respectively. The uncertainty in the atomic weight of zinc was reduced by more than an order of magnitude. The publication of partial data resulted in the revision of the value of the atomic weight of zinc by the International Union of Pure and Applied Chemistry.</p>","PeriodicalId":17018,"journal":{"name":"Journal of Research of the National Bureau of Standards. Section A, Physics and Chemistry","volume":"79A 6","pages":"747-759"},"PeriodicalIF":0.0,"publicationDate":"1975-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6589414/pdf/jres-79A-747.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"37747050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
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