Ben Fathallah Ons, Lembei Anastasiya, Rey Michael, Mondelain Didier, Campargue Alain
CNRS, LIPhy, University Grenoble Alpes, 38000 Grenoble, France.
GSMA, UMR CNRS 7331, University of Reims Champagne Ardenne, Moulin de la Housse B.P. 1039, F-51687 CEDEX Reims, France.
Molecules. 2024 Nov 8;29(22):5276. doi: 10.3390/molecules29225276.
Monodeuterated methane (CHD) contributes greatly to absorption in the 1.58 μm methane transparency window. The spectrum is dominated by the 3ν band near 6430 cm, which is observed in natural methane and used for a number of planetary applications, such as the determination of the D/H ratio. In this work, we analyze the CHD spectrum recorded by high-sensitivity differential absorption spectroscopy in the 6099-6530 cm region, both at room temperature and at 81 K. Following a first contribution to this topic by Lu et al., the room-temperature line list is elaborated (11,189 lines) and combined with the previous 81 K list (8962 lines) in order to derive about 4800 empirical lower-state energy values from the ratio of the line intensities measured at 81 K and 294 K (2-method). Relying on the position and intensity agreements with the TheoReTS variational line list, about 2890 transitions are rovibrationally assigned to twenty bands, with fifteen of them being newly reported. Variational positions deviate from measurements by up to 2 cm, and the band intensities are found to be in good agreement with measurements. All the reported assignments are confirmed by Ground-State Combination Difference (GSCD) relations; i.e., all the upper-state energies (about 1370 in total) have coinciding determinations through several transitions (up to 8). The energy values, determined with a typical uncertainty of 10 cm, are compared to their empirical and variational counterparts. The intensity sum of the transitions assigned between 6190 and 6530 cm represents 76.9 and 90.0% of the total experimental intensities at 294 K and 81 K, respectively.
单氘代甲烷（CHD）对1.58μm甲烷透明窗口的吸收有很大贡献。该光谱由6430cm附近的3ν带主导，这在天然甲烷中也能观察到，并用于许多行星应用，例如D/H比的测定。在这项工作中，我们分析了通过高灵敏度差分吸收光谱法在6099 - 6530cm区域记录的CHD光谱，包括室温下和81K时的光谱。继Lu等人首次对该主题做出贡献之后，我们精心编制了室温下的谱线列表（11189条谱线），并将其与之前的81K谱线列表（8962条谱线）相结合，以便根据在81K和294K测量的谱线强度之比（2 - 方法）得出约4800个经验性的低能级能量值。基于与TheoReTS变分谱线列表的位置和强度一致性，约2890个跃迁被振转归属到二十个谱带，其中十五个是新报道的。变分位置与测量值的偏差高达2cm，并且发现谱带强度与测量值吻合良好。所有报道的归属都通过基态组合差（GSCD）关系得到了证实；即，所有的高能级能量（总共约1370个）通过几个跃迁（多达8个）有一致的测定结果。所确定的能量值典型不确定度为10cm，并与它们的经验值和变分值进行了比较。在6190至6530cm之间归属的跃迁强度总和分别占294K和81K时总实验强度的76.9%和90.0%。
