Radiation damage in coronene, rubrene and p-terphenyl, measured for incident electrons of kinetic energy between 100 and 200 keV

被引:31
作者
Li, P [1 ]
Egerton, RF [1 ]
机构
[1] Univ Alberta, Dept Phys, Edmonton, AB T6G 2J1, Canada
基金
加拿大自然科学与工程研究理事会;
关键词
radiation damage; cathodoluminescence; scanning electron microscopy; electron energy-loss spectroscopy;
D O I
10.1016/j.ultramic.2004.05.010
中图分类号
TH742 [显微镜];
学科分类号
摘要
We have measured the sensitivity of three highly conjugated organic compounds to electron irradiation. Using a 200 keV TEM, loss of crystallinity was determined from quantitative electron-diffraction measurements. Degradation of the molecular ring structure was monitored from fading of the 6 eV pi-excitation peak in the energy-loss spectrum. Measurements at incident energies between 30 keV and 100 eV were made using a scanning electron microscope (SEM), by recording gradual decay of the cathodoluminescence (CL) signal. Expressed in Grays, the energy dose required for CL decay in coronene is a factor of 30 lower than for destruction of crystallinity and a factor of 300 lower than for destruction of the molecular structure. Below 1 keV, the CL-decay cross section shows no evidence of a threshold effect, indicating that the damage involved is caused by valence-electron (rather than K-shell) excitation. Therefore even relatively radiation-resistant organic materials may undergo some form of damage when examined in a low-energy electron microscope or a low-voltage SEM. (C) 2004 Elsevier B.V. All rights reserved.
引用
收藏
页码:161 / 172
页数:12
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