Lifetime and electronic state interference and ultrafast dissociation of inner-shell resonant Raman excited CO, NO, CO2, and N2O investigated by photon-induced fragment-fluorescence spectrometry (PIFS)

通过光子诱导碎片荧光光谱 (PIFS) 研究内壳共振拉曼激发 CO、NO、CO2 和 N2O 的寿命和电子态干扰以及超快解离

• 批准号: 66946523
• 负责人: Professor Dr. Arno Ehresmann
• 金额: --
• 依托单位: Experimentalphysik IV: Funktionalisierte dünne Schichten und Physik mit Synchrotronstrahlung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/66946523?language=en
• 关键词: Lifetime; electronic; state; interference; ultrafast

Inner-shell resonance decay processes of molecules after their excitation by synchrotron radiation (electron emission processes, like Auger/double Auger decays or ultrafast dissociative processes, like Coulomb explosion) are prototypes for the test of basic quantum mechanics and are, therefore, the topic of intense current research. In the present project two aspects of these decay processes will be investigated in a fresh experimental approach, where excitation by small bandwidth monochromatized synchrotron radiation is used together with high resolution (dispersed) fragment fluorescence spectrometry and polarimetry (photon-induced fluorescence spectrometry, PIFS) to determine absolute fragment-state selective fragmentation cross sections as functions of the exciting-photon energy: 1) Lifetime vibrational interference (LVI) and electronic state interference (ESI) effects, and 2) ultrafast dissociation. This as yet very scarcely applied experimental approach will be combined with elaborate ab-initio calculations by a co-operating group for a quantitative comparison between experiment and theory. The decays of molecular inner shell resonances are strongly influenced by lifetime vibrational interference (LVI) and electronic state interference (ESI), due to closely neighbouring vibronic or electronic resonant states, overlapping partly within their natural linewidths. PIFS experiments, partly with polarization analysis of the emitted fluorescence, will be used to investigate experimentally LVI and ESI in the inner-shell resonantly excited heteroatomic molecules CO and NO. For these molecules it is possible to compare the decay of inner shell resonances strongly influenced by LVI and ESI effects (excitation of the O1s electron) with the decay of resonances weaker influenced (excitation of the C1s or N1s electron in CO or NO, respectively). Ultrafast dissociation processes of the inner-shell resonances will be investigated by dispersively monitoring the fluorescence emission of excited neutral fragments. These fragments cannot be emitted by the Coulomb explosion mechanism and are an indication of a very fast dissociation process competing with the abundant autoionization mechanisms for the deexcitation of the resonances. Finally, we will start to investigate fragmentation processes of the triatomic molecules CO2 and N2O after vibration-state selective inner-shell excitation of the C1s (N1s) and O1s electrons into molecular excited CO+ (N2+ and NO+) fragments by recording dispersedly CO+ (N2+ and NO+) fluorescence in well-known wavelength ranges, being therefore state-selective to the CO+ (N2+ and NO+) fragment state.

分子在同步辐射激发后的内壳层共振衰变过程（电子发射过程，如俄歇/双俄歇衰变或超快解离过程，如库仑爆炸）是基本量子力学测试的原型，因此是当前研究的热门话题。在本项目中，这些衰变过程的两个方面将在一个新的实验方法中进行研究，其中小带宽单色同步辐射的激发与高分辨率一起使用（分散）碎片荧光光谱法和旋光法（光子诱导荧光光谱法，PIFS）以确定作为激发光子能量的函数的绝对碎片态选择性碎片化截面：1）寿命振动干涉（LVI）和电子态干涉（ESI）效应，以及2）超快解离。这个还很少应用的实验方法将与一个合作小组精心设计的从头计算相结合，以便在实验和理论之间进行定量比较。分子内壳层共振的衰减强烈地受到寿命振动干涉（LVI）和电子态干涉（ESI）的影响，这是由于紧密相邻的振动或电子共振态，在它们的自然线宽内部分重叠。PIFS实验，部分与偏振分析的发射荧光，将被用于实验研究LVI和ESI在内壳层共振激发的杂原子分子CO和NO中。对于这些分子，可以比较LVI和ESI效应强烈影响的内壳层共振衰减（O 1 s电子的激发），共振衰减的影响较弱（分别在CO或NO中C1 s或N1s电子的激发）。超快解离过程的内壳层共振将研究通过分散监测激发中性碎片的荧光发射。这些碎片不能由库仑爆炸机制发射，并且是非常快速的解离过程的指示，该过程与大量的自电离机制竞争共振的去激发。最后，我们将开始研究三原子分子CO2和N2 O在C1 s（N1s）和O 1 s电子的振动态选择性内壳层激发成分子激发态CO+后的碎裂过程（N2+和NO+）碎片通过分散记录CO+（N2+和NO+）荧光，因此对CO+（N2+和NO+）碎片状态具有状态选择性。