Standard frequencies - TITLE H1

Recommended values of standard frequencies

info - m

All the radiations in the list (apart from the ⁸⁷Rb 6.8 GHz transition) may be used for the practical realization of the definition of the metre.

The information is available in PDF format below or in machine-readable form from our API service.

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Please also find the data associated with the 2021 adjustment of standard frequencies.

Supplementary documentation for the 2021 calculation

info - s

The radiations marked [SRS] may be used as secondary representations of the second.

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Wavelength ≈ 237 nm

Wavelength ≈ 243 nm

Wavelength ≈ 265 nm

Wavelength ≈ 267 nm

Wavelength ≈ 282 nm

Wavelength ≈ 436 nm

Wavelength ≈ 467 nm

Wavelength ≈ 515 nm

Wavelength ≈ 531 nm

Wavelength ≈ 532 nm

Wavelength ≈ 543 nm

Wavelength ≈ 576 nm

Wavelength ≈ 578 nm

Wavelength ≈ 606 nm

Wavelength ≈ 612 nm

Wavelength ≈ 633 nm

Wavelength ≈ 633 nm

Wavelength ≈ 640 nm

Wavelength ≈ 657 nm

Wavelength ≈ 674 nm

Wavelength ≈ 698 nm

Wavelength ≈ 698 nm

Wavelength ≈ 729 nm

Wavelength ≈ 778 nm

Wavelength ≈ 780 nm

Wavelength ≈ 1.54 µm

Wavelength ≈ 3.39 µm

Wavelength ≈ 10.3 μm

Standard frequencies - TITLE H1

Recommended values of standard frequencies

info - m

info - s

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