| 摘要: |
| 石英E1′心是一种重要的顺磁性缺陷，其热活化ESR信号强度的最大值有许多新的应用，但对于获取E1′心信号强度最大值的方法尚存不同的认识。为了进一步研究和探讨石英E1′心信号的增强机理及石英E1′心ESR信号强度最大值的获取方法，采用电子自旋共振（ESR）技术测量了两个冰碛物样品在300℃等温加热前和加热后石英E1′心的ESR信号强度，结果表明：在室温下，石英E1′心信号强度随辐照剂量的增加而增强是由于伪E1′心的形成而造成的；而石英E1′心信号强度随辐照剂量增加而减弱可能是因为辐照使已增强的E1′心产生衰退。300℃的等温热退火实验（分为15 min和20 min）结果表明：获取E1′心ESR信号强度的最大值需要人工辐照，人工辐照的作用不仅是提供更多的空穴，而且可能更有利于氧空位向E1′心转化。 |
| 关键词: 石英E1′心 ESR信号强度 伪E1′心 等温热退火实验 |
| DOI：10.7515/JEE182054 |
| CSTR：32259.14.JEE182054 |
| 分类号: |
| 基金项目:国家自然科学基金项目（41230523）；中国科学院战略性先导科技专项（XDA20070102） |
| 英文基金项目:National Natural Science Foundation of China (41230523); Strategic Priority Research Program of Chinese Academy of Sciences (XDA20070102) |
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| Study on the thermal activation of electron spin resonance (ESR) signal intensity in quartz E1′ center |
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LI Miao, YI Chaolu, BI Weili, YANG Haijun, QIU Dengfeng
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1. Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China
4. Department of Chemistry, Tsinghua University, Beijing 100084, China
5. State Key Laboratory for Oil and Gas Enrichment Mechanism and Effective Development of Shale, Laboratory of Structural and Sedimentary Reservoirs of the Sinopec Petroleum Exploration and Development Institute, Beijing 100083, China
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| Abstract: |
| Background, aim, and scope The E1′ center in quartz is an important paramagnetic defect, and the maximum value of its thermal activation ESR signal intensity has many new applications. However, there are different views on the method for obtaining the maximum value of the E1′ center intensity. Therefore, in order to further study and discuss the enhancement mechanism of the quartz E1′ center and the condition for obtaining the maximum ESR signal intensity of the quartz E1′ center, it is important to carry out the study on the thermal activation of ESR signal intensity in quartz E1′ center. Materials and methods The Sample A was collected from the bottom part of the moraine in the Urumqi Valley of Xinjiang, China. And the Sample B was collected from the surface part of the moraine in Purog Kangri, Tibetan Plateau. The samples were irradiated by artificial gamma rays at different doses, and then the E1′center signal intensities of the samples were measured by electron spin resonance (ESR) technology before and after the 300℃ isothermal heating. Results At room temperature, the intensity of the E1′ signal of Sample A is enhanced with the increase of irradiation dose, while the intensity of the E1′ signal of Sample B descends first and then rises gradually with the increase of radiation dose. After heating at 300℃ for 15 min, the E1′ center signal intensities of Sample A increases first with the increase of radiation dose, and then saturates above 400 Gy. For another set of aliquots of Sample A which are heated at 300℃ for 20 min, the E1′ center signal intensities are basically the same. For Sample B, the E1′ center signal intensities of the unirradiated (0 Gy) aliquots are smaller than that of the irradiated aliquots, regardless of heating for 15 min or 20 min. Discussion The signal intensity of the E1′ center is enhanced with the increase of irradiation dose at room temperature due to the formation of the counterfeit E1′ center, while the intensity of E1′ center decreases with the increase of radiation dose may due to the gamma ray irradiation cause the real E1′ center to decay. For the one set of aliquots of Sample A which are heated at 20 min at 300℃, the signal intensity of the E1′ center are basically the same indicate that the amount of the holes in the Sample A is sufficient, and the E1′ signal intensities of the another set of aliquots of Sample A which are heated at 300℃ for 15 min increase first with the increase of radiation dose and then saturate above 400 Gy show that the irradiation can facilitate the conversion of oxygen vacancies to E1′ center. After the isothermal heating at 300℃ for 15 min or 20 min, the E1′ center signal intensities of the unirradiated (0 Gy) aliquots of Sample B are smaller than that of the irradiated aliquots indicate that radiation can produce more holes, so that all oxygen vacancies can be transformed into E1′ center. Conclusions Gamma irradiation would enhance the intensity of the counterfeit E1′ center, but can reduce the real E1′ center signal intensity. In order to obtain the maximum value of the E1′ signal intensity, the pre-irradiation is needed and the effect of artificial irradiation is not only to provide more holes, but also to facilitate the conversion of oxygen vacancies to E1′ center. Recommendations and perspectives The maximum value of the quartz E1′ center signal intensity is not only related to irradiation, but also related to temperature. Therefore, in order to get the maximum value of E1′ center signal intensity more accurately, more study on the thermal activation characteristics of the ESR signal intensity of quartz E1′ center should be carried out. |
| Key words: quartz E1′ center ESR signal intensity counterfeit E1′ isothermal annealing experiment |
