Laboratory of Theoretical Spectroscopy, Institute of Atmospheric, Optics, Russian Academy of Sciences, 634055 Tomsk, Russia.
Phys Chem Chem Phys. 2013 Jul 7;15(25):10071-93. doi: 10.1039/c3cp50799h. Epub 2013 May 29.
We present the first detailed analysis of the infrared spectrum of methane (12)CH4 in the so-called Tetradecad region from 2.1 to 1.6 μm (4760-6250 cm(-1)). New experimental high resolution FTIR spectra at 78 K and at room temperature combined with improved theoretical modeling have allowed quantum assignments to be greatly extended in this region. A global fit of all assigned lines of (12)CH4 in the 0-6200 cm(-1) region has been performed. In the end, 3012 line positions and 1387 intensities of 45 individual subbands of the Tetradecad were modeled up to J = 14. The root mean square deviations were 0.023 cm(-1) for line positions and 13.86% for line intensities in the Tetradecad region itself. Although this analysis is still preliminary, it is already sufficient to characterize the stronger bands throughout the whole of the Tetradecad. The calculated integrated intensity of the polyad is 1.399 × 10(-19) cm(-1)/(molecule cm(-2)) at 296 K. A "definitive" theoretical modeling of this spectral region of methane requires further work, but the present success substantially improves our understanding of methane spectroscopy as needed to interpret planetary atmospheres. Lines pertaining to three-fourths of the 60 sub-vibrational bands in this polyad have been assigned.
我们首次详细分析了 2.1 到 1.6 μm（4760-6250 cm(-1)) 所谓的十四烷区甲烷(12)CH4 的红外光谱。新的实验在 78 K 和室温下的高分辨率傅里叶变换红外光谱，结合改进的理论模型，使这一区域的量子分配得到了极大的扩展。在 0-6200 cm(-1) 区域对(12)CH4 的所有分配线进行了全局拟合。最终，对十四烷的 45 个独立子带的 3012 条线位置和 1387 条强度进行了建模，直到 J = 14。在十四烷区内，线位置的均方根偏差为 0.023 cm(-1)，线强度的均方根偏差为 13.86%。尽管这种分析仍然是初步的，但已经足以描述整个十四烷中较强的谱带。在 296 K 时，多聚体的计算积分强度为 1.399×10(-19) cm(-1)/(分子 cm(-2))。要对甲烷这一光谱区域进行“明确”的理论建模还需要进一步的工作，但目前的成功大大提高了我们对甲烷光谱学的理解，这是解释行星大气所必需的。该多聚体中三分之二的 60 个亚振动带的谱线已经被分配。
