Infrared Resonance Enhanced Multi Photon Ionization of Fullerenes
Infrared Resonance Enhanced Multi Photon Ionization of Fullerenes
复制标题
富勒烯的红外共振增强多光子电离
DOI：
10.1109/eqec.1998.714913
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
G. Meijer
中科院分区：
文献类型：
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作者：
G. Meijer
气相富勒烯被来自自由电子激光器（FEL）的一系列高功率亚皮秒脉冲共振加热到内部能量，在该内部能量下，它们有效地进行延迟电离而很少或没有碎片[1]。当激光从6-20 μm调谐，同时记录激光产生的母离子量时，观察到200-600个红外光子的共振吸收，所得波长谱与C_（60）的红外吸收谱非常相似。利用自由电子激光的红外共振增强多光子电离（IR-REMPI）技术，可以实现对气相富勒烯的质量选择性检测。为了深入了解电离机制，记录IR激发后离子产生的时间演变。离子产生出乎意料地慢，在激光激发后超过0.1 ms时发生。结果表明，达到第一电子激发态是从热分子到离子的一个高障碍。
Gas-phase fullerenes are resonantly heated by a train of high power subpicosecond pulses from a Free Electron Laser (FEL) to internal energies at which they efficiently undergo delayed ionization with little or no fragmentation [1]. When the laser is tuned from 6–20 μm while the amount of laser produced parent ions is recorded, resonant absorption of 200–600 IR photons is observed and the resulting wavelength spectra have a close resemblance to the IR absorption spectrum of C60. InfraRed Resonance Enhanced Multi Photon Ionization (IR-REMPI) with a FEL enables extremely sensitive IR spectroscopy with mass selective detection of gas-phase fullerenes. To gain insight into the ionization mechanism, the time evolution of the production of the ions following IR excitation is recorded. Ion creation is unexpectedly slow, occurring at times beyond 0.1 ms after laser excitation. The results indicate that reaching the first electronically excited state is a high hurdle on the way from hot molecules to ions.