The fragment of the 1-methylpyrene cation, ${\mathrm{C}}_{17}{\mathrm{H}}_{11}^{+}$, is expected to exist in two isomeric forms, 1-pyrenemethylium ${\mathrm{PyrCH}}_2^{+}$ and the tropylium containing species ${\mathrm{PyrC}}_7^{+}$. We measured the infrared (IR) action spectrum of cold ${\mathrm{C}}_{17}{\mathrm{H}}_{11}^{+}$ tagged with Ne using a cryogenic ion trap instrument coupled to the FELIX laser. Comparison of the experimental data with density functional theory calculations allows us to identify the ${\mathrm{PyrCH}}_2^{+}$ isomer in our experiments. The IR Multi-Photon Dissociation spectrum was also recorded following the C₂H₂${\mathrm{C}}_2{\mathrm{H}}_2$ loss channel. Its analysis suggests combined effects of anharmonicity and isomerisation while heating the trapped ions, as shown by molecular dynamics simulations.

1-甲基芘阳离子的片段， ${\mathrm{C}}_{17}{\mathrm{H}}_{11}^{+}$，预计以两种异构形式存在，1-芘甲基 ${\mathrm{PyrCH}}_2^{+}$ 和含镎的物种 ${\mathrm{PyrC}}_7^{+}$. 我们测量了冷的红外 (IR) 作用光谱${\mathrm{C}}_{17}{\mathrm{H}}_{11}^{+}$ 使用与 FELIX 激光器耦合的低温离子阱仪器用 Ne 标记。实验数据与密度泛函理论计算的比较使我们能够确定${\mathrm{PyrCH}}_2^{+}$ 我们实验中的异构体。在C ₂ H ₂之后还记录了 IR 多光子解离光谱${\mathrm{C}}_2{\mathrm{H}}_2$ 损失通道。其分析表明，在加热捕获的离子时，非谐性和异构化的综合影响，如分子动力学模拟所示。