Ultraviolet photodissociation (UVPD) experiments of protonated tryptamine ([Tryp+H]⁺) have been implemented by a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer combined with a wavelength-tunable optical parametric oscillator (OPO) laser. UVPD mass spectra under different laser wavelengths have been obtained, in which the dependence of the yield of fragment ions on the laser wavelength was observed. The UVPD spectrum of [Tryp+H]⁺ has been obtained in the range of 210–310 nm. Besides the previously reported two competitive channels of H loss and NH₃ loss, two important channels of losing CH₂NH and CH₂NH₂ units were observed and further studied by UV–UV tandem mass spectrometry and theoretical calculations. Interestingly, results show that the pair of competitive channels of CH₂NH loss and CH₂NH₂ loss are both from the McLafferty-type rearrangement caused by ππ* electronic excited states. After the excitation, the two different dissociation pathways produce two different ion–neutral complexes, respectively. The wavelength-dependent dissociation and the existing competitive channels shown in this study reflect the diversity of UVPD processes of such organic molecules.

中文翻译：

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质子化色胺的波长依赖性紫外光解离。

质子化色胺（[Tryp + H] ⁺）的紫外光解离（UVPD）实验已经通过傅立叶变换离子回旋共振（FTICR）质谱仪与波长可调光学参量振荡器（OPO）激光结合进行。获得了不同激光波长下的UVPD质谱图，其中观察到碎片离子的收率与激光波长的相关性。[Tryp + H] ⁺的UVPD光谱在210–310 nm范围内获得。除了先前报道的H丢失和NH ₃丢失的两个竞争通道外，CH ₂ NH和CH ₂ NH ₂丢失的两个重要通道通过UV-UV串联质谱法和理论计算观察并进一步研究了单位。有趣的是，结果表明，CH ₂ NH损失和CH ₂ NH ₂损失的竞争通道对都是由ππ*电子激发态引起的McLafferty型重排。激发后，两种不同的解离途径分别产生两种不同的离子-中性络合物。这项研究中显示的波长依赖性解离和现有竞争通道反映了这种有机分子的UVPD过程的多样性。