Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR CNRS 7583, University Paris-Est Créteil (UPEC) and University Paris Diderot, Institut Pierre Simon Laplace , 61 Avenue du Général de Gaulle, 94010 Créteil Cedex, France.
J Phys Chem A. 2013 Dec 19;117(50):13236-48. doi: 10.1021/jp401979v. Epub 2013 May 21.
A new line position analysis of the ν3 and ν4 bands of nitric acid (HNO3) at 1326.186 and 1303.072 cm(-1) together with its associated interacting bands is presented. The 3(1) and 4(1) energy levels were obtained from an extended analysis of high-resolution Fourier transform spectra recorded at Giessen in the 7.6 μm region. The energy levels of 3(1) and 4(1) upper states of nitric acid are strongly interacting with those of the 9(3), 6(2), 5(1)9(1), and 7(1)8(1) dark states centered at 1288.899, 1289.46, 1341.05, and 1343.78 cm(-1), respectively. Informations on these perturbing dark states were achieved through previous partial investigations of hot bands in high-resolution Fourier transform spectra recorded at 22 μm in Giessen (for 3ν9-2ν9 and 3ν9-ν5), at 12 μm in Denver (for 3ν9-ν9), and at 11 μm in Orsay (for ν5+ν9-ν9). The energy levels calculation accounts for the various Fermi, anharmonic, A-type, B-type, and C-type Coriolis resonances, which couple together the {6(2),9(3),4(1),3(1),5(1)9(1),7(1)8(1)} interacting energy levels. For nitric acid, the ν9 mode (OH torsion relative to the -NO2 moiety) is a large amplitude motion. The theoretical model used in this work accounts also for large amplitude effects in the 9(3) dark state, which lead to a splitting of the 9(3) energy levels of about 0.060 cm(-1). In this way, the existence of torsional splittings for several ν4 perturbed lines was explained by the occurrence of local A-type and B-type Coriolis resonances coupling the 4(1) energy levels with those of 9(3). Because four dark bands had to be accounted for in the model, the results of the energy level calculations are reasonable, although not perfect. However, a very significant improvement was achieved in terms of understanding the 7.6 μm absorbing bands of nitric acid as compared to the analysis of the ν3 and ν4 bands performed several years ago [Perrin, A.; Lado-Bordowski, O.; Valentin, A. Mol. Phys. 1989, 67, 249-267]. Finally, the present analysis also features, for the first time, the ν3+ν9-ν9 hot band located at 1331.09 cm(-1). This study will help to improve HNO3 measurements by satellites. This will be indeed the case for the "Infrared Atmospheric Sounding Interferometer" (IASI) experiment.
本文报道了硝酸（HNO3）ν3 和 ν4 带在 1326.186 和 1303.072 cm(-1)的新的线位置分析，以及与其相关的相互作用带。通过对吉森在 7.6 μm 区域记录的高分辨率傅里叶变换光谱的扩展分析，获得了 3(1)和 4(1)能级。HNO3 的 3(1)和 4(1)上能级与中心位于 1288.899、1289.46、1341.05 和 1343.78 cm(-1)的 9(3)、6(2)、5(1)9(1)和 7(1)8(1)暗态的能级强烈相互作用。这些扰动暗态的信息是通过以前在吉森（用于 3ν9-2ν9 和 3ν9-ν5）、丹佛（用于 3ν9-ν9）和奥尔赛（用于 ν5+ν9-ν9）在 22 μm、12 μm 和 11 μm 记录的高分辨率傅里叶变换光谱中对热带的部分研究获得的。能级计算考虑了各种费米、非谐、A 型、B 型和 C 型科里奥利共振，这些共振将相互作用能级{6(2)、9(3)、4(1)、3(1)、5(1)9(1)、7(1)8(1)}耦合在一起。对于硝酸，ν9 模式（相对于-NO2 部分的 OH 扭转）是一个大振幅运动。本文工作中使用的理论模型还考虑了 9(3)暗态中的大振幅效应，这导致 9(3)能级的分裂约为 0.060 cm(-1)。通过这种方式，通过发生局部 A 型和 B 型科里奥利共振，将 4(1)能级与 9(3)能级耦合在一起，解释了几条 ν4 受扰线的扭转分裂的存在。由于模型中必须考虑四个暗带，因此能级计算的结果是合理的，尽管不是完美的。然而，与几年前对 ν3 和 ν4 带的分析相比，在理解硝酸的 7.6 μm 吸收带方面取得了显著的进展[Perrin, A.; Lado-Bordowski, O.; Valentin, A. Mol. Phys. 1989, 67, 249-267]。最后，本次分析还首次展示了位于 1331.09 cm(-1)的 ν3+ν9-ν9 热带。这项研究将有助于通过卫星改进 HNO3 的测量。对于“红外大气探测干涉仪”（IASI）实验确实如此。
