# Determination of the Avogadro constant by counting the atoms in a 28Si crystal.

@article{Andreas2011DeterminationOT, title={Determination of the Avogadro constant by counting the atoms in a 28Si crystal.}, author={Birk Andreas and Yasushi Azuma and Guido Bartl and Peter Becker and Horst Bettin and Michael Borys and Ingo Busch and Malcolm Gray and Paul Fuchs and Kenichi Fujii and Hiroyuki Fujimoto and Ernest G. Kessler and Michael Krumrey and Ulrich Kuetgens and Naoki Kuramoto and Giovanni Mana and Peter Manson and Enrico Massa and Shigeki Mizushima and Arnold Nicolaus and Alain Picard and Axel Pramann and Olaf Rienitz and Detlef Schiel and Staf Valkiers and Atsushi Waseda}, journal={Physical review letters}, year={2011}, volume={106 3}, pages={ 030801 } }

The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the…

## 209 Citations

### Molar-mass measurement of a 28Si-enriched silicon crystal for determination of the Avogadro constant

- Chemistry
- 2014

The molar mass of a 28Si-enriched crystal was measured at the National Metrology Institute of Japan to determine the Avogadro constant by the x-ray crystal density method as part of the International…

### The new kilogram definition based on counting the atoms in a 28Si crystal

- Chemistry
- 2012

The kilogram is the only unit of measure still defined by a physical object. Now, a marathon effort to tie the kilogram to a constant of nature is nearing the finish line. This paper concerns an…

### Determination of the atomic weight of 28Si-enriched silicon for a revised estimate of the Avogadro constant.

- ChemistryAnalytical chemistry
- 2012

Using the results generated herein for A(r)(Si) along with other IAC measurement results for mass, volume, and the lattice spacing, the estimate of the Avogadro constant becomes N(A) = 6.022 140 40(19) × 10(23) mol(-1).

### Avogadro constant determination for a redefined kilogram

- Physics
- 2011

Today the mass unit kilogram is still defined by the mass of an artefact, the international prototype of the kilogram. The Avogadro constant can be used to define the kilogram in terms of a…

### Elemental characterization of the Avogadro silicon crystal WASO 04 by neutron activation analysis

- Chemistry
- 2012

Impurity measurements of the 28Si crystal used for the determination of the Avogadro constant are essential to prevent biased results or underestimated uncertainties. A review of the existing data…

### Realization of the kilogram by the XRCD method

- Physics
- 2016

When the kilogram is redefined in terms of the fixed numerical value of the Planck constant h, the x-ray-crystal-density (XRCD) method, among others, is used for realizing the redefined kilogram. The…

### Improved measurement results for the Avogadro constant using a 28Si-enriched crystal

- Physics
- 2015

New results are reported from an ongoing international research effort to accurately determine the Avogadro constant by counting the atoms in an isotopically enriched silicon crystal. The surfaces of…

### Accurate measurements of the Avogadro and Planck constants by counting silicon atoms

- Physics
- 2013

Fundamental constants link seemingly different fields of physics and seemingly different quantities and measurement units. Consequently, they are of the utmost interest in metrology and it has been…

### Mass Measurement of 1-kg Silicon Spheres for Determination of the Avogadro and Planck Constants

- PhysicsIEEE Transactions on Instrumentation and Measurement
- 2015

The amount of the physical adsorption of water vapor on the surface of the silicon spheres, which could be a relative amount of about 10-8 of the total mass, was evaluated by comparison weighings both in nitrogen gas and in water vapor at a pressure of about 1200 Pa.

### Absolute silicon molar mass measurements, the Avogadro constant and the redefinition of the kilogram

- Environmental Science
- 2014

The results of an absolute silicon molar mass determination of two independent sets of samples from the highly 28Si-enriched crystal (AVO28) produced by the International Avogadro Coordination are…

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