Kamer Jerry, Schleier Domenik, Jiao Andy, Schneider Grégory, Martens Jonathan, Berden Giel, Oomens Jos, Bouwman Jordy
Laboratory for Astrophysics, Leiden Observatory, Leiden University, 2300 RA Leiden, The Netherlands.
Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin 10623, Germany.
Phys Chem Chem Phys. 2024 Nov 13;26(44):27912-27921. doi: 10.1039/d4cp03004d.
Infrared emission features are observed towards diverse astronomical objects in the interstellar medium (ISM). Generally, the consensus is that these IR features originate from polycyclic aromatic hydrocarbons (PAHs) and are hence named aromatic infrared bands (AIBs). More recently, it has been suggested that nitrogen substituted PAHs (PANHs) contribute to the AIBs as well and it has even been shown that nitrogen inclusion in PAHs can improve the match with the AIBs, specifically around the 6.2 μm feature. In order to determine which specific molecules or functional groups are at the origin of the AIBs, IR spectra of various PA(N)Hs are experimentally and computationally studied. In this work we expand on the spectroscopic investigation of PANHs by presenting the gas-phase mid-IR spectra of 1,5,9-triazacoronene˙ (, / 303), a threefold nitrogenated congener of coronene˙, its protonated derivative (/ 304) and the product that forms when water adds to dehydrogenated (/ 320). We analyze the mid-IR spectra by comparing them with vibrational modes calculated at the B3LYP/6-311++G(d,p) level a theory and we present a possible geometry for . The mid-IR spectrum is compared to that of coronene˙ and is demonstrated to be remarkably similar. We put and into astronomical context by comparing their recorded mid-IR spectra to observed ISM spectra of four spectral classes. From this we conclude that and could both contribute to the AIBs, with being a more likely contributor than .
在星际介质（ISM）中，朝向各种天体观测到了红外发射特征。一般来说，人们普遍认为这些红外特征源自多环芳烃（PAHs），因此被称为芳香红外带（AIBs）。最近，有人提出氮取代的多环芳烃（PANHs）也对AIBs有贡献，甚至有人表明多环芳烃中包含氮可以改善与AIBs的匹配，特别是在6.2μm特征附近。为了确定哪些特定分子或官能团是AIBs的起源，对各种PA(N)Hs的红外光谱进行了实验和计算研究。在这项工作中，我们通过展示1,5,9 - 三氮杂蒄˙（，/ 303）的气相中红外光谱来扩展对PANHs的光谱研究，1,5,9 - 三氮杂蒄˙是蒄˙的三倍氮化同系物，其质子化衍生物（/ 304）以及水加到脱氢的（/ 320）上形成的产物。我们通过将中红外光谱与理论计算在B3LYP/6 - 311++G(d,p)水平下的振动模式进行比较来分析中红外光谱，并给出了的一种可能几何结构。将的中红外光谱与蒄˙的中红外光谱进行比较，结果表明它们非常相似。通过将记录的中红外光谱与四种光谱类别的观测到的ISM光谱进行比较，我们将和置于天文学背景中。由此我们得出结论，和都可能对AIBs有贡献，比更有可能是贡献者。
