Wavelength Modulation Absorption Spectroscopy Using a Frequency-Quadruped Current-Modulated System

A wavelength modulation absorption spectrometry (WMAS) with a frequency-quadruped system is demonstrated. The frequency-quadruped system consists of a two-frequency doubled external enhancement cavity with KNO₃ and BBO crystals, and a current-modulated 906-nm single mode external cavity diode laser (ECDL), which generates the tunable wavelength modulated radiation at 226.7 nm used to detect the NO absorption line that belongs to the combined Q₂₂(10.5) and ^QR₁₂(10.5) lines of γ(0,0) band within the A^2_Σ+ -X²Π electronic transition system. The 1^st, 2 ^nd and 3^rd harmonic spectra are accomplished to show that it is possible to detect samples using the frequency quadruped system combined with the WMAS technique that can find practical applicability in the future.