Merging Complementary Techniques in Laboratory Spectroscopy for Remote Sensing Applications

分子光谱学使我们能够识别不容易到达的位置的分子，例如地球大气层的上层，星际云以及其他行星，彗星和冷恒星的大气。光谱线的形状为我们提供了一个“窗口”，使我们能够了解控制辐射吸收和发射的机制，并超越迄今为止所接受的经典图像来解释它们。除了分子鉴定和定量外，光谱技术还可以提供有关偏远环境的物理性质的信息。 这是在大气研究中广泛使用的遥感的基础。非常精确的光谱测量线形可以帮助我们了解分子动力学的基本过程，并在遥感数据的解释。从遥感光谱中提取信息需要从实验室光谱学和理论模型中获得量子态分辨数据（线位置，强度和形状）。 有一个越来越多的需要高度准确的汇编线参数的分子是常见的各种天体物理环境，包括系外行星大气。这是由于越来越多的高分辨率望远镜和仪器的可用性，包括赫歇尔，未来的JWST，飞机基如索菲亚，以及地面基如阿尔马。对于许多感兴趣的分子，行列表需要能够跨越大的温度范围，因为它们存在于跨越宽温度范围的不同环境中。 我建议调查N2 O3，一项事业，这是最具挑战性的，因为N2 O3的化学不稳定性和各种实验技术和理论建模，包括从头计算的组合，是必需的。拟议的研究的目标是获得更准确的信息，在不对称的低躺在红外波段-和可能的双晶-N2 O3通过记录，第一次，高分辨率的远红外光谱的冷却混合物的NO和NO2/N2 O 4。 实验室实验中的浓度误差可以通过以下方法来克服：使用激光光谱仪在同一样品上同时测量8-10 µm左右的合适红外光谱，该激光光谱仪将从我们的实验室重新定位，并通过高分辨率傅里叶变换光谱（FTS）同时记录纯旋转光谱来确定实际浓度。 因此，该项目的成功完成需要两种实验技术相结合：傅里叶变换红外光谱和二极管激光光谱。 该提议的一部分也是对冷巨行星和热系外行星行星大气中甲烷的近红外研究。我建议使用的理论和高分辨率的实验相结合，以确定高精度的线参数的H 2加宽甲烷的K波段的功能。测量将集中在a）4450和4700 cm-1之间的较弱的线，使用冷温度（215 - 296 K）的冷巨行星的新光谱，以及B）4300 - 4450 cm-1之间的较强线，使用太阳系外行星（例如热彗星）的高温（296 - 350 K）光谱。 所测得的H2加宽线宽，压力变化，和温度依赖性指数系数将使精确的线，线计算的温度范围很广。这项研究将支持使用地面和空间观测（现在和未来）分析行星和系外行星大气，并将使理论家能够扩展他们的“甲烷全球分析”。

Molecular spectroscopy allows us to identify molecules in locations not easily accessible, such as the upper layers of the Earth’s atmosphere, interstellar clouds, and the atmospheres of other planets, comets and of cool stars. It is the shape of a spectral line that provides a “window” for us to look inside the mechanism governing the absorption and emission of radiation and interpret them beyond the classical pictures accepted so far. In addition to molecular identification and quantitation, spectroscopic techniques can provide information on the physical properties of remote environments. This is the basis of remote sensing which is used extensively in atmospheric studies. Extremely precise spectral measurements of a line shape can help us understand fundamental processes of molecular dynamics and in the interpretation of remote sensing data. Extracting information from remote sensing spectra requires quantum state-resolved data (line positions, intensities, and shapes) from both laboratory spectroscopy and from theoretical models. There is an increasing need for highly accurate compilations of line parameters of molecules that are common in various astrophysical environments including exoplanet atmospheres. This is being driven by the availability of ever increasingly high-resolution telescopes and instruments, including space-based such as Herschel, the future JWST, plane-based such as SOFIA, and ground based such as ALMA. For many of the molecules of interest, the line lists need to be able to span a large temperature range since they exists in different environments that span a wide temperature range. I propose to investigate N2O3, an undertaking that is most challenging because of the chemical instability of N2O3 and the fact that combinations of various experimental techniques and theoretical modelling, including ab initio calculations, are required. The goal of the proposed research is to obtain more accurate information on the low lying infrared bands in asymmetric- and possibly symmetric-N2O3 by recording, for the first time, the high resolution far-infrared spectrum of a cooled mixture of NO and NO2/N2O4. The concentration errors in the laboratory experiments can be overcome by measuring simultaneously, and on the same sample, suitable IR absorptions around 8-10 µm with a laser spectrometer that will be re-located from our lab for the experiments, and to determine the actual concentration by simultaneously recording the pure rotational spectrum by high resolution Fourier Transform Spectroscopy (FTS). Therefore, the successful completion of the project requires two experimental techniques to be combined: Fourier Transform Infrared Spectroscopy and diode laser spectroscopy. Part of this proposal is also a near infrared study of methane for planetary atmospheres of cold giant planets and hot exoplanets. I propose to use a combination of theory and high-resolution experiments to determine highly accurate line parameters of H2-broadened methane features in the K band. The measurements will focus on a) weaker lines between 4450 and 4700 cm-1, using new spectra at cold temperatures (215 – 296 K) for cold giant planets, and b) stronger lines in the 4300 – 4450 cm-1 using spectra at elevated temperatures (296 – 350 K) for extra-solar planets (e.g. hot-Jupiters). The measured H2-broadened linewidths, pressure-shifts, and temperature dependence exponent coefficients will enable accurate line-by-line calculations for a wide range of temperatures. This study will support analyses of planetary and exoplanetary atmospheres using ground-, and space-based observations (present and future) and will allow the theorists to extend their “global analysis of methane”.