Absolute frequency list of the v3-band transitions of methane at a relative uncertainty level of 10-11

Sho Okubo, Hirotaka Nakayama, Kana Iwakuni, Hajime Inaba, Hiroyuki Sasada

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


We determine the absolute frequencies of 56 rotationvibration transitions of the v3 band of CH4 from 88.2 to 90.5 THz with a typical uncertainty of 2 kHz corresponding to a relative uncertainty of 2.2 × 10-11 over an average time of a few hundred seconds. Saturated absorption lines are observed using a difference-frequency-generation source and a cavity-enhanced absorption cell, and the transition frequencies are measured with a fiber-laser-based optical frequency comb referenced to a rubidium atomic clock linked to the international atomic time. The determined value of the P(7) F2(2) line is consistent with the International Committee for Weights and Measures recommendation within the uncertainty.

Original languageEnglish
Pages (from-to)23878-23888
Number of pages11
JournalOptics Express
Issue number24
Publication statusPublished - 2011 Nov 21

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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