Douglas-Walker Thomas E, Campbell Ewen K, Daly Francis C, Douin Stéphane, Gans Bérenger, Jacovella Ugo, Maurice Colombe, Odant Robin, Palotás Julianna
School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, King's Buildings, Edinburgh EH9 3FJ, Scotland, U.K.
Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France.
ACS Earth Space Chem. 2024 Nov 21;8(12):2644-2651. doi: 10.1021/acsearthspacechem.4c00272. eCollection 2024 Dec 19.
Identification of the molecular carriers of diffuse interstellar bands (DIBs) requires gas phase electronic spectra of suitable candidate structures. Recording the spectra of these in the laboratory is challenging because they include large, carbon-rich molecules, many of which are likely to be ionic. The electronic spectra of ions are often obtained using action spectroscopy methods, which can induce small perturbations to the absorption characteristics and hinder comparison with astronomical observations. In this contribution, the appropriateness of helium-tagging and two-color resonant-enhanced photodissociation spectroscopy as suitable techniques to obtain the requisite laboratory data for comparison to DIBs is explored. As a proof-of-concept, the C̃ B ← X̃ B electronic transition of the phenylacetylene cation (PA, CH ), obtained by helium-tagging and two-color photodissociation, is compared to the direct absorption spectrum recorded using cavity ring-down spectroscopy. The results indicate that for DIBs with typical widths of a few ångströms, the wavelengths, bandwidths, and relative intensities from action spectroscopy are obtained with sufficient precision to facilitate accurate comparisons to catalogued DIBs.
识别弥漫星际带（DIBs）的分子载体需要合适候选结构的气相电子光谱。在实验室中记录这些光谱具有挑战性，因为它们包含大型的富碳分子，其中许多可能是离子型的。离子的电子光谱通常使用光解光谱法获得，这种方法会对吸收特性产生微小扰动，并妨碍与天文观测结果的比较。在本论文中，我们探讨了氦标记和双色共振增强光解光谱法作为获取与DIBs比较所需实验室数据的合适技术的适用性。作为概念验证，将通过氦标记和双色光解获得的苯乙炔阳离子（PA，CH ）的C̃ B ← X̃ B电子跃迁与使用腔衰荡光谱记录的直接吸收光谱进行了比较。结果表明，对于典型宽度为几埃的DIBs，光解光谱法获得的波长、带宽和相对强度具有足够的精度，便于与编目DIBs进行准确比较。
