The Search for Carriers of Diffuse Interstellar Bands

漫射星际带（DIB）是在可见光和近红外波段观测到的星际介质（ISM）致密区域的吸收特征。为了确定载体的DIBs，我们建议测量几类分子的吸收线，预测或证明存在于天体物理environments.Objectives的主要注意力将被给予长碳链（>15个C原子）。尽管是有希望的候选人的DIB载体的作用，他们的光谱从来没有被测量，因为他们的生产由自下而上的化学在高温下是有限的小链。虽然短碳链的光谱被深入研究，并且在ISM中没有发现这些分子除了C3之外的吸收带，但是所有这些研究都只探测了第一电子跃迁，这是相当弱的。碳链长度的增加在检测到DIB的位置处带来强吸收带，并且这些强带的强度比先前研究的跃迁高至少两个数量级。因此，即使是中等丰度的这些物种在ISM将提供一个吸收，可以detected.Methods我们将使用在以前的联合项目，使我们能够大大提高光谱数据收集的质量和速度开发的实验技术。这种阳离子光谱技术提供了冷阳离子的数据，其质量对于与天体物理观测进行直接比较是必要的，与其他现有的实验方法相比，其速度要高得多。这使得它可以测试更多的物种，从而增加了机会，以确定新的载体的DIBs。水平的originalityThe使用的He液滴技术将允许自由基的测量所形成的低温化学或通过分裂的母分子在电离过程中。这提供了对难以或不可能以其他方式测量的物种的访问。知识的振子强度的电子跃迁对应的吸收带，这是没有检测到的天文观测，允许估计的上限丰度的相应物种的ISM。这提供了关于在这些区域中发生的化学反应以及在相同区域中可以检测到来自相同类别的其他分子的概率的有用信息。所有这些预期的结果使目前提出的识别DIB携带者的尝试达到了一个全新的水平。由奥地利（保罗Scheier）和德国（Serge Krasnokutski）PI监督的学生。实现拟议目标需要双方伙伴的专门知识和投入。

Wider research context Diffuse interstellar bands (DIBs) are absorption features of dense areas of the interstellar medium (ISM) observed in the visible and near-infrared ranges. To identify the carriers of DIBs, we suggest to measure absorption lines of several classes of molecules that were predicted or proven to exist in astrophysical environments.Objectives The main attention will be given to long carbon chains (>15 C atoms). In spite of being promising candidates for the role of DIB carriers, their spectra have never been measured since their production by bottom-up chemistry at high temperatures is limited to small chains. Although the spectroscopy of short carbon chains was intensely studied, and no absorption bands of these molecules besides C3 were found in the ISM, all these studies probed only first electronic transitions, which are quite weak. The increase of the carbon chain length brings strong absorption bands in the position where DIBs are detected and the intensity of these strong bands are at least two orders of magnitude higher compared to the previously studied transitions. Thus even moderate abundances of these species in the ISM would provide an absorption that can be detected.Methods We will use experimental techniques developed in the previous joint project that allows us to considerably improve the quality and speed of spectral data collection. This technique of cation spectroscopy provides data of cold cations in a quality necessary for the direct comparison with astrophysical observations, at a much higher rate compared to other currently existing experimental methods. This makes it possible to test a larger number of species and consequently increases the chances to identify new carriers of DIBs.Level of originalityThe use of the He droplet technique will allow the measurement of radicals that are formed either by low-temperature chemistry or via fragmentation of parent molecules during the ionization. This provides access to species that are hard or impossible to measure in other ways. Knowledge of the oscillator strength of electronic transition corresponding to absorption bands, which are not detected in astronomical observations, allows estimating an upper limit of the abundance of the corresponding species in the ISM. This provides useful information on the chemistry occurring in these areas and on the probability that other molecules from the same class can be detected in the same areas. All these expected results bring the currently proposed attempt of identification of carriers of DIBs to a completely new level.Primary researchers involved The proposed studies will be carried out by two Ph.D. students supervised by the Austrian (Paul Scheier) and German (Serge Krasnokutski) PIs. Expertise and input of both partners are required to achieve the proposed goals.