Determination of the Avogadro Constant

Deslattes, R; Henins, Albert; Bowman, Horace A.; Schoonover, Randall M.; Carroll, Colleen; Barnes, I. L.; Machlan, L. A.; Moore, L. J.; Shields, William R.

doi:10.1103/physrevlett.33.463

Cited by 192 publications

(76 citation statements)

References 14 publications

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“…In 1965, Bonse & Hart [14] realized the first X-ray interferometer, thus paving the way to the accomplishment of this dream, and Deslattes [6] with a relative uncertainty of 3.0 × 10 −8 . The majority of the material reported here can also be found in more detail in Andreas et al [15].…”

Section: Results and Outlookmentioning

confidence: 99%

“…In this way, the difficult absolute calibration of the mass spectrometer with the required small uncertainty could be overcome by applying isotope dilution mass spectrometry combined with multi-collector inductively coupled plasma mass spectrometry. In his pioneering work on the Avogadro constant determination, Deslattes also foresaw in 1974 the need for enriched silicon to improve mass measurement uncertainties [6].…”

Section: Introductionmentioning

confidence: 99%

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The Avogadro constant: determining the number of atoms in a single-crystal ²⁸ Si sphere

Becker

Bettin

2011

Phil. Trans. R. Soc. A.

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The Avogadro constant, the number of entities in an amount of substance of one mole, links the atomic and the macroscopic properties of matter. Since the molar Planck constant-the product of the Planck constant and the Avogadro constant-is very well known via the measurement of the Rydberg constant, the Avogadro constant is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a new definition of the kilogram in terms of a fundamental constant. Here, we describe a new and unique approach to determine the Avogadro constant from the number of atoms in 1 kg single-crystal spheres that are highly enriched with the 28 Si isotope. This approach has enabled us to apply isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, N A = 6.022 140 82(18) × 10 23 mol −1 , is now the most accurate input datum for a new definition of the kilogram.

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Section: Results and Outlookmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Avogadro constant: determining the number of atoms in a single-crystal ²⁸ Si sphere

Becker

Bettin

2011

Phil. Trans. R. Soc. A.

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“…At very low thicknesses, the critical angle is determined by the density of the silicon substrate. This is the best known of all densities, since it is used in the determination of the Avogadro number (9). Errors in the density of the oxide have a negligible effect on the determination of the thickness.…”

Section: Traceability Of X-ray Reflectivity Methodsmentioning

confidence: 99%

X-ray metrology for ULSI structures

Bowen¹,

Matney²,

Wormington³

1998

The 1998 International Conference on Characterization and Metrology for ULSI Technology

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Non-destructive X-ray metrological methods are discussed for application to both process development and process control of ULSI structures. X-ray methods can (a) detect the unacceptable levels of internal defects generated by RTA processes in large wafers, (b) accurately measure the thickness and roughness of layers between 1 and 1000 nm thick and (c) can monitor parameters such as crystallographic texture and the roughness of buried interfaces. In this paper we review transmission X-ray topography, thin film texture measurement, grazing-incidence X-ray reflectivity and high-resolution X-ray diffraction. We discuss in particular their suitability as on-line sensors for process control.

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“…The next major improvement in the uncertainty of the Avogadro constant came with the first measurement based on a pure crystal of silicon [13]. The application of the XRCD methods to a silicon crystal, together with the use of an X-ray method capable of giving a value for the lattice constant in the SI metre, was a breakthrough.…”

Section: Advances In the Determination Of The Avogadro Constantmentioning

confidence: 99%

“…This approach was foreseen by Deslattes as the best way to minimize the uncertainty owing to the measurement of the atomic weight [13], and is described elsewhere [14].…”

Section: Advances In the Determination Of The Avogadro Constantmentioning

confidence: 99%

A new definition for the mole based on the Avogadro constant: a journey from physics to chemistry

Milton

2011

Phil. Trans. R. Soc. A.

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The mole is the most recent addition to the set of base units that form the International System of Units, although its pre-cursor the 'gram-molecule', had been in use by both physicists and chemists for more than 120 years. A proposal has been published recently to establish a new definition for the mole based on a fixed value for the Avogadro constant. This would introduce consistent relative uncertainties for the molar and the atomic masses while making no change to the system of relative atomic masses ('atomic weights'). Although the proposal would have little impact on the measurement uncertainty of practical work, it has stimulated considerable debate about the mole and the nature of the quantity amount of substance. In this paper, the rationale for the new definition is explained against the background of changes in the way the quantity amount of substance has been used, from its first use during the early development of thermodynamics through to the use of the 'number of gram-molecules' at the end of the nineteenth century.

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Determination of the Avogadro Constant

Cited by 192 publications

References 14 publications

The Avogadro constant: determining the number of atoms in a single-crystal ²⁸ Si sphere

The Avogadro constant: determining the number of atoms in a single-crystal ²⁸ Si sphere

X-ray metrology for ULSI structures

A new definition for the mole based on the Avogadro constant: a journey from physics to chemistry

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Determination of the Avogadro Constant

Cited by 192 publications

References 14 publications

The Avogadro constant: determining the number of atoms in a single-crystal 28 Si sphere

The Avogadro constant: determining the number of atoms in a single-crystal 28 Si sphere

X-ray metrology for ULSI structures

A new definition for the mole based on the Avogadro constant: a journey from physics to chemistry

Contact Info

Product

Resources

About

The Avogadro constant: determining the number of atoms in a single-crystal ²⁸ Si sphere

The Avogadro constant: determining the number of atoms in a single-crystal ²⁸ Si sphere