High-Resolution Absorption Cross Sections of Formaldehyde in the 30285–32890 cm–1 (304–330 nm) Spectral Region

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2012-06, Vol.116 (24), p.5910-5922
• Main Authors: Tatum Ernest, Cheryl, Bauer, Dieter, Hynes, Anthony J
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp210008g

Absolute room temperature (294 ± 2 K) absorption cross sections for the Ã1A2–X̃1A1 electronic transition of formaldehyde have been measured over the spectral range 30285–32890 cm–1 (304–330 nm) using ultraviolet (UV) laser absorption spectroscopy. Accurate high-resolution absorption cross sections are essential for atmospheric monitoring and understanding the photochemistry of this important atmospheric compound. Absorption cross sections were obtained at an instrumental resolution better than 0.09 cm–1, which is slightly broader than the Doppler width of a rotational line of formaldehyde at 300 K (∼0.07 cm–1) and so we were able to resolve all but the most closely spaced lines. Comparisons with previous data as well as with computer simulations have been made. Pressure broadening was studied for the collision partners He, O2, N2, and H2O and the resulting broadening parameters have been measured and increase with the strength of intermolecular interaction between formaldehyde and the collision partner. The pressure broadening coefficient for H2O is an order of magnitude larger than the coefficients for O2 and N2 and will contribute significantly to spectral line broadening in the lower atmosphere. Spectral data are made available as Supporting Information.