Determination Of Avogadro Research Articles

Volume determination of two spheres of the new 28Si crystal of PTB

In the scope of the redetermination of Avogadro’s constant NA, a new isotopically enriched silicon crystal has been produced, from which two spheres were manufactured. After the crystal properties, the lattice parameter and molar mass, as well as the masses of the two spheres have been determined, the volume of the spheres was also measured. For this, the sphere interferometer of PTB was used. The methods of the interferometric measurements have been improved and the major contributions to the uncertainty have been investigated thoroughly. As a result, the total uncertainty could be reduced significantly, yielding a substantial impact on the determination of Avogadro’s constant. The mean diameter of each sphere was measured twice with a repeatability of ±2 × 10−10, and the relative uncertainty of the ‘apparent’ volume, which disregards the comparatively small influence of the optical effects of surface layers, was reduced to 7 × 10−9. The final results of the volumes and comments on their uncertainties are given.

Filling the voids in silicon single crystals by precipitation of Cu3Si

This article presents a method to decorate all open volume defects in a silicon single crystal by Cu3Si precipitation. Si single crystals are being used for the determination of Avogadro's number with sufficient accuracy (1 part in 108) to allow the establishment of a physical standard for the kilogram. The method described here can be used to certify that the open volume in such crystals is sufficiently small. The voids in this work were formed artificially by annealing He-implanted silicon wafers. Annealing after application of a copper nitrate solution to the surface followed by slow cooling produced Cu3Si precipitates in the η′ phase in the voids. To fill all the voids completely it proved necessary to coat the surfaces, after application of the nitrate, with a pure Cu layer as well. Slow cooling keeps the supersaturation of Cu small but sufficient to precipitate Cu into the voids. Formation of dislocation loops and stacking faults, often seen during Cu silicide precipitation in silicon after fast cooling, can be minimized. Other transition metals, such as Au, Ni, and Fe, were found to be less suitable than Cu for filling voids.

Determination of Avogadro's Number by Improved Electroplating

A quick and accurate measurement of Avogadro‘s number from the amount of plated material can be made using a modification of an established electrolytic experiment. The experiment was modified to prevent loss of the copper plated at the cathode (copper plate) as a result of poor plating. The copper plating thus obtained was a firmly bonded and smooth layer, and the percent error of the results was reduced from approximately 20% to about 1% (the small error remaining is caused by the ammeter limits, not loss of plated mass). Control of the current during the experiment was also easier. If copper is not available it can be replaced by commonly available, inexpensive metals such as iron, zinc, or nickel.

Determination of Avogadro’s number (An experiment)

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Channel noise in nerve membranes and lipid bilayers.

The basic principles underlying fluctuation phenomena in thermodynamics have long been understood (for reviews see Kubo, 1957; Kubo, Matsuo & Kazuhiro 1973 Lax, 1960). Classical examples of how fluctuation analysis can provide an insight into the corpuscular nature of matter are the determination of Avogadro's number according to Einstein's theory of Brownian motion (see, e.g. Uhlenbeck & Ornstein, 1930; Kac, 1947) and the evaluation of the electronic charge from the shot noise in vacuum tubes (see Van der Ziel, 1970).

Determination of Avogadro's number with a scintillation counter

Determination of Avogadro's number with a scintillation counter

Determination of Avogadro's number by Perrin's law

The experimental procedure for determining Avogadro's number by the Perrin method includes preparing a monodisperse colloid, ascertaining the mass of the particles, and making an accurate count of the number of particles at two points in the equilibrated colloid.

A new determination of Avogadro’s number from lattice constant and density of single crystals

The previous values of Avogadro's number determined from the lattice constant and density of single crystals are listed. The differences in these values are noted, and possible errors are discussed. Among these are lattice- constants error, diffraction-angle error, material error, systematic errors, and density error. In this new determination, these crystals were used: Al, CaF₂, CsI, Ge, Si, SiO₂, TlCl, and TlBr. When the most unreliable values are disregarded, this value agrees with that of Birge within

A note on the determination of the Avogadro number

Problems involved in the determination of Avogadro's number by using x- ray data are discussed, with emphasis on determination or crystal density and the effects or imperfect crystals. (M.H.R.)

Absolute Value of Avogadro's Number and the Soundness of Crystals

The experimental determination of Avogadro's number by the x-ray-density method is uncertain because of imperfections in crystals. It is proposed to regard the lattice of purest calcite as a reference lattice because of its proximity to a sound lattice, and to accept the value ${N}_{0}=6.02567\ifmmode\times\else\texttimes\fi{}{10}^{23}$ g ${\mathrm{mole}}^{\ensuremath{-}1}$ (phys.) which is equivalent to 6.02403\ifmmode\times\else\texttimes\fi{}${10}^{23}$ g ${\mathrm{mole}}^{\ensuremath{-}1}$ (chem.) for Avogadro's number as derived from measurements on pure calcite. The perfection of the lattices of all other crystalline substances then would be determined in comparison with the calcite as either sound (equal in perfection to that of calcite) within the error limits or as defective (vacancies, interstitial atoms), using the number above for the calculations.

The determination of Avogadro's number from observation on bacteria (Cocci): J. H. Shaxey. (Proc. Royal Soc., A 728.)

The determination of Avogadro's number from observation on bacteria (Cocci): J. H. Shaxey. (Proc. Royal Soc., A 728.)

A new determination of Avogadro's constant

A new determination of Avogadro's constant

A Determination of Avogadro's ConstantNfrom Measurements of the Brownian Movements of Small Oil Drops Suspended in Air

A Determination of Avogadro's Constant<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>N</mml:mi></mml:math>from Measurements of the Brownian Movements of Small Oil Drops Suspended in Air