Comparison of cross-section measurements of the 2ν5 overtone band of formaldehyde determined by cavity ringdown and cavity enhanced spectroscopy

We have measured the integrated cross-section of a transition at 5676.08 cm−1 in the 2ν5 overtone band of formaldehyde to be (3.09 ± 0.10) × 10−23 cm2 cm−1 by cavity ringdown spectroscopy using a tunable diode laser. This measurement was used to calculate the integrated cross-section of the QR1(10) line at 5676.21 cm−1 as (5.8 ± 0.5) × 10−22 cm2 cm−1. We compare this figure to our value of this cross-section measured using the technique of cavity enhanced absorption spectroscopy of (5.7 ± 0.6) × 10−22 cm2 cm−1 and find the results to be in good agreement.