期刊
CHEMICAL SCIENCE
卷 10, 期 46, 页码 10706-10715出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9sc04100a
关键词
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资金
- US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division within the in situ TEM program [DE-AC02-05-CH11231, KC22ZH]
- National Natural Science Foundation of China (NSFC) [61722402, 61574059, 91833302]
- National Key Research and Development Program of China [2016YFB0700700]
- Shanghai Academic/Technology Research Leader [19XD1421300]
- Fok Ying Tung Education Foundation [161060]
- Fundamental Research Funds for the Central Universities
- CC of ECNU
Radiolysis ionization under electron beam illumination induces dissociation and damage of organic and biological molecules; thus, it is impossible to image the related materials by transmission electron microscopy (TEM). To understand the atomistic mechanism of radiolysis damage, we developed a systematical procedure based on real-time time-dependent density functional theory (rt-TDDFT) for simulating the radiolysis damage processes of molecules; this procedure can describe the ionization cross sections of the electronic states and the fast dissociation processes caused by hot carrier cooling and the Auger decay on deep levels. For the radiolysis damage of C2H6O2, our simulation unexpectedly showed that there is strong competition among three different dissociation paths, including fast dissociation caused by nonadiabatic cooling of the hot carrier; fast dissociation caused by Auger decay, which induces double ionization and Coulomb explosion; and slow dissociation caused by increased kinetic energy. As the energy of the incident electron beam changes, the time scales of these dissociation paths and their relative contributions to the molecule damage change significantly. These simulation results explain the measured mass spectra of the C2H6O2 dissociation fragments and also provide clear competition mechanisms for blocking these dissociation paths in the TEM imaging of organic and biological materials.
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