We research the adsorption geometries graphene （Li-GR） before and after CO and electronic structures of pristine graphene （p-GR） and Li-doped adsorption by first-principles. The adsorption energies Ead of CO on p-...We research the adsorption geometries graphene （Li-GR） before and after CO and electronic structures of pristine graphene （p-GR） and Li-doped adsorption by first-principles. The adsorption energies Ead of CO on p-GR and Li-GR are calculated. The results demonstrate that Ead of CO on Li-GR is from -3.3 eV to -3.5 eV, meanwhile Q is up to 0.13e, which indicate that strong electrostatic attractions occur between CO and Li-GR, while CO is physically adsorbed on p-GR. The obvious accumulated charge in electron density difference and increasing carrier density suggest that the conductivity of Li-GR is improved considerably after CO adsorp- tion. An adsorption mechanism is also proposed. Our results provide a path to achieving CO sensors with high performance.展开更多
放射性碘是核环境保护的重要监测内容。目前,碘监测仪均采用圆柱形活性炭取样盒,由均匀分布的标准体源进行效率标定,很难模拟实际测量中碘在活性炭盒中的分布情况,因此无法准确标定其探测效率。为了检验碘监测仪探测效率的准确性,利用...放射性碘是核环境保护的重要监测内容。目前,碘监测仪均采用圆柱形活性炭取样盒,由均匀分布的标准体源进行效率标定,很难模拟实际测量中碘在活性炭盒中的分布情况,因此无法准确标定其探测效率。为了检验碘监测仪探测效率的准确性,利用蒙特卡罗软件MCNP(Monte Carlo N Particle Transport Code),模拟计算了EIM型碘监测仪对碘在活性炭取样盒内呈不同分布情况下的探测效率,并进行验证。同时建立的碘监测仪探测效率的蒙特卡罗模型,为改进仪器设计,提高探测效率的准确度提供参考。结果表明:对于与探测器同轴的井型活性炭采样盒,使用均匀分布体源标定碘监测仪的探测效率准确度较高。展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 51372282,51072024 and 51132002the National College Students’Innovative and Entrepreneurial Training Program of Beijing Institute of Technology under Grant No201410007050
文摘We research the adsorption geometries graphene （Li-GR） before and after CO and electronic structures of pristine graphene （p-GR） and Li-doped adsorption by first-principles. The adsorption energies Ead of CO on p-GR and Li-GR are calculated. The results demonstrate that Ead of CO on Li-GR is from -3.3 eV to -3.5 eV, meanwhile Q is up to 0.13e, which indicate that strong electrostatic attractions occur between CO and Li-GR, while CO is physically adsorbed on p-GR. The obvious accumulated charge in electron density difference and increasing carrier density suggest that the conductivity of Li-GR is improved considerably after CO adsorp- tion. An adsorption mechanism is also proposed. Our results provide a path to achieving CO sensors with high performance.
文摘放射性碘是核环境保护的重要监测内容。目前,碘监测仪均采用圆柱形活性炭取样盒,由均匀分布的标准体源进行效率标定,很难模拟实际测量中碘在活性炭盒中的分布情况,因此无法准确标定其探测效率。为了检验碘监测仪探测效率的准确性,利用蒙特卡罗软件MCNP(Monte Carlo N Particle Transport Code),模拟计算了EIM型碘监测仪对碘在活性炭取样盒内呈不同分布情况下的探测效率,并进行验证。同时建立的碘监测仪探测效率的蒙特卡罗模型,为改进仪器设计,提高探测效率的准确度提供参考。结果表明:对于与探测器同轴的井型活性炭采样盒,使用均匀分布体源标定碘监测仪的探测效率准确度较高。
