Division of Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, United States.
J Phys Chem A. 2012 Jun 21;116(24):5910-22. doi: 10.1021/jp210008g. Epub 2012 Feb 3.
Absolute room temperature (294 ± 2 K) absorption cross sections for the Ã(1)A(2)-X̃(1)A(1) electronic transition of formaldehyde have been measured over the spectral range 30,285-32,890 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, O(2), N(2), and H(2)O 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 H(2)O is an order of magnitude larger than the coefficients for O(2) and N(2) and will contribute significantly to spectral line broadening in the lower atmosphere. Spectral data are made available as Supporting Information.
在绝对室温（294 ± 2 K）下，使用紫外（UV）激光吸收光谱法，在 30285-32890 cm-1（304-330nm）的光谱范围内，测量了甲醛的Ã(1)A(2)-X̃(1)A(1)电子跃迁的绝对吸收截面。准确的高分辨率吸收截面对于大气监测和理解这种重要大气化合物的光化学至关重要。吸收截面是在仪器分辨率优于 0.09 cm-1 的条件下获得的，这略宽于 300 K 时甲醛的旋转线的多普勒宽度（约 0.07 cm-1），因此我们能够分辨出除了最接近的线之外的所有线。与以前的数据以及计算机模拟进行了比较。研究了碰撞伙伴 He、O(2)、N(2)和 H(2)O 对甲醛的压力展宽，测量了由此产生的展宽参数，并随着甲醛与碰撞伙伴之间的分子间相互作用强度的增加而增加。H(2)O 的压力展宽系数比 O(2)和 N(2)的系数大一个数量级，并且将在低层大气中显著影响光谱线展宽。光谱数据作为支持信息提供。
