Kivimäki Antti, Stråhlman Christian, Richter Robert, Sankari Rami
Nano and Molecular Systems Research Unit, University of Oulu , P.O. Box 3000, 90014 Oulu, Finland.
MAX IV Laboratory, Lund University , P.O. Box 118, 22100 Lund, Sweden.
J Phys Chem A. 2018 Jan 11;122(1):224-233. doi: 10.1021/acs.jpca.7b11250. Epub 2017 Dec 28.
We have studied the fragmentation of the methanol molecule after core excitation and core ionization by observing coincidences between negative and positive ions. Five different negative ions (H, C, CH, O, and OH) were observed at both the C 1s and O 1s edges. As negative ion formation occurs after resonant and normal Auger decay of core-hole states, it is necessarily linked with the release of positively charged fragments. Our data show that such fragmentation can happen in many different ways: We found approximately 30 negative-ion/positive-ion/positive-ion coincidence (NIPIPICO) channels. All involve only singly charged positive ions. Fragmentation channels leading to atomic ions are the most probable, but positive molecular ions are also frequently found in the context of anion formation. Coincidence yields as a function of photon energy were determined for the most intense NIPIPICO channels. Adding together the data measured at different photon energies, we could also verify the occurrence of four-ion coincidences, which involved one negative ion (H or O) and three positive ions.
我们通过观察负离子和正离子之间的符合情况，研究了甲醇分子在芯激发和芯电离后的碎片化过程。在碳1s和氧1s边缘均观察到了五种不同的负离子（H、C、CH、O和OH）。由于负离子的形成发生在芯空穴态的共振和正常俄歇衰变之后，它必然与带正电碎片的释放相关联。我们的数据表明，这种碎片化可以通过多种不同方式发生：我们发现了大约30个负离子/正离子/正离子符合（NIPIPICO）通道。所有通道仅涉及单电荷正离子。导致原子离子的碎片化通道最有可能出现，但在负离子形成的情况下也经常发现正分子离子。针对最强烈的NIPIPICO通道，确定了符合产率作为光子能量的函数。将在不同光子能量下测量的数据相加，我们还可以验证四离子符合的发生情况，其中涉及一个负离子（H或O）和三个正离子。
