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System for scanning hydrogen cyanide absorption lines
Hošek, Martin ; Řeřucha, Šimon ; Hrabina, Jan ; Čížek, Martin ; Pravdová, Lenka ; Číp, Ondřej
The definition of both meter and second relies on precisely measured frequency. The convenient sources of such frequencies are lasers stabilized by molecular vapours. The He-Ne lasers stabilized by iodin vapours represent the cornerstone sources in the visible spectrum. On the other hand, the infrared spectrum (particularly the 1550 nm C-band) is of metrological interest thanks to its cost-effective, readily available components. The widely used absorption media at 1550 nm has been two acetylene isotopes (12C2H2, 13C2H2), while H13C14N represents an alternative covering a wider spectrum well corresponding to the telecommunication C-band. The 2ν3 rotational-vibrational band had been investigated, but due to the use of not-so-precise methods, the presented data feature high uncertainty compared to acetylene data. We represent methods that will lead to precise assessments of hydrogen cyanide's absorption line centres with the potential to introduce HCN to Mise en Pratique, making it an internationally recognized source of precise frequency for the realization of traceable laser etalons.
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