Desorption Dynamics of Tetracene Ion from Tetracene-doped Anthracene Crystals Studied by Femtosecond Time-Resolved Mass Spectrometry
Desorption Dynamics of Tetracene Ion from Tetracene-doped Anthracene Crystals Studied by Femtosecond Time-Resolved Mass Spectrometry
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飞秒时间分辨质谱研究并四苯离子从并四苯掺杂蒽晶体中的解吸动力学
DOI：
10.1021/jp210884p
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Tatsuya Fujino
中科院分区：
文献类型：
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作者：
Yuuki Minegishi;Daisuke Morimoto;Jun Matsumoto;Haruo Shiromaru;Kenro Hashimoto;Tatsuya Fujino
利用飞秒时间分辨质谱研究了并四苯离子（[tetracene]+）在蒽-并四苯高效能量转移的TDA晶体中的脱附动力学.利用400 nm的泵浦脉冲，TDA晶体中的蒽分子被激发到S1态。在一定的泵浦延迟（<10 ps）后，S1蒽中的激发能转移到并四苯分子中产生S1态。在S1状态的并四苯，然后电离的时间延迟的探测脉冲（266 nm）和解吸并四苯离子从晶体进行监测与飞行时间质谱仪。在时间分辨质谱上，并四苯离子的峰强度随延迟时间的增加而逐渐增加。对于蒽/并四苯浓度比为1：0.02和1：0.01的TDA晶体，并四苯离子的上升时间常数（被认为是从晶体中解吸的时间）分别被确定为80.8和94.7 ps。并四苯离子的脱附时间随激发功率的增大而缩短。处于高振动激发态的S_0蒽是由电子激发的蒽分子通过内转换或激子-激子湮灭产生的，储存在蒽中的过量振动能被认为是解离模振动激发的来源，从而导致并四苯离子的脱附。我们还认为，目前的过程，其中包括电子弛豫和多余的振动能量在基质分子的基态的生产，是在传统的基质辅助激光解吸电离（MALDI）的分析物的解吸机制。
The desorption dynamics of tetracene ion ([tetracene]+) from tetracene-doped anthracene (TDA) crystals in which efficient energy transfer from anthracene to tetracene occurs was investigated by means of femtosecond time-resolved mass spectrometry. Using a 400 nm pump pulse, anthracene molecules in TDA crystals are initially excited to the S1state. After a certain delay (<10 ps) of pumping, the excitation energy in the S1anthracene is transferred to a tetracene molecule to produce the S1state. Tetracene in the S1state is then ionized by a time-delayed probe pulse (266 nm) and desorbed tetracene ions from the crystals are monitored with a time-of-flight mass spectrometer. On the time-resolved mass spectra, the peak intensity of the tetracene ions shows a gradual increase with increasing delay time. The rise time constant of tetracene ion, which is considered to the desorption time from the crystals, was determined to be 80.8 and 94.7 ps for TDA crystals with anthracene/tetracene concentration ratios of 1:0.02 and 1:0.01, respectively. The desorption time of tetracene ion became short with increasing excitation power. The S0anthracene at the highly vibrationally excited state is produced by internal conversion or exciton–exciton annihilation of electronically excited anthracene molecules, and the excess vibrational energy stored in anthracene is considered to be the origin of the vibrational excitation of dissociative modes, which leads to the desorption of tetracene ions. We also consider that the present process, which includes electronic relaxation and the production of excess vibrational energy in the ground state of matrix molecules, is the mechanism for the desorption of analyte in conventional matrix-assisted laser desorption ionization (MALDI).