The helium-tagging technique was employed to record absorption spectra of cold anthracene cations and protonated anthracene. The evaluation of the spectra of the chromophore with a different number of attached He atoms allows getting the precise band positions of the molecular ions in the gas phase. The positions of the two most intense bands of anthracene, suitable for astrophysical detection, were found to be λ _max = 3478.9 1.8 Å and λ _max = 7068.9 5.7 Å. A considerable shift of the red band position compared to a previous measurement was attributed to a temperature effect. No coincidence of the absorption bands in astrophysical observational spectra was found. This allows estimating the upper limit for the abundance of anthracene cations per H nuclei <10⁻⁹ along the HD 183143 line of sight. We discuss possible reasons for such a low abundance of this molecular ion.

氦标记技术用于记录冷蒽阳离子和质子化蒽的吸收光谱。评估具有不同数量的附着 He 原子的发色团的光谱，可以获得分子离子在气相中的精确带位置。发现适用于天体物理检测的两个最强烈的蒽带的位置是λ _max = 3478.9 1.8 Å 和λ _max = 7068.9 5.7 Å。与之前的测量相比，红带位置发生了相当大的变化，这归因于温度效应。没有发现天体物理观测光谱中吸收带的重合。这允许估计每个 H 核 <10 的蒽阳离子丰度的上限^-9沿 HD 183143 视线。我们讨论了这种分子离子丰度如此低的可能原因。