利用含时密度泛函(Time-Dependent Density Functional Theory,TDDFT)方法在6-311++g**基组水平上研究了外电场对碳原子线前十个激发态特性和能级分布的影响.结果表明不同大小、不同方向的电场对碳原子线激发态和能级分布影响各不相同....利用含时密度泛函(Time-Dependent Density Functional Theory,TDDFT)方法在6-311++g**基组水平上研究了外电场对碳原子线前十个激发态特性和能级分布的影响.结果表明不同大小、不同方向的电场对碳原子线激发态和能级分布影响各不相同.其中沿分子轴方向较高的电场对碳原子线能级影响较为明显,影响了电子在分子中的输运,从而对碳原子线伏安特性产生一定的影响.展开更多
利用碳原子线(CAWs)上的羧基与2-巯基乙胺的氨基发生选择性缩合反应生成巯基化碳原子线,并用红外光谱对反应进程及一些反应条件的影响进行表征.实验结果表明:10 mg经浓硝酸氧化处理过的碳原子线在含有20 mg巯基乙胺、10 mL CH2Cl2、1 mL...利用碳原子线(CAWs)上的羧基与2-巯基乙胺的氨基发生选择性缩合反应生成巯基化碳原子线,并用红外光谱对反应进程及一些反应条件的影响进行表征.实验结果表明:10 mg经浓硝酸氧化处理过的碳原子线在含有20 mg巯基乙胺、10 mL CH2Cl2、1 mL N(Et)3(三乙胺)、0.2 g DCC(二环己基碳化二亚胺)的液相反应体系中,60℃温度下作用24 h可完成缩合反应,生成巯基化碳原子线.在该巯基化过程中,CAWs的特征碳链结构并未发生可觉察的变化.展开更多
The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cub...The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cubic(fcc)structure.Here we report the structural,mechanical and physical properties of the refractory(Nb_(0.375)Ta_(0.25)Mo_(0.125)W_(0.125)Re_(0.125))_(100−x)C_(x) HEAs over a wide x range of 0≤x≤20.It is found that,whereas the starting HEA(x=0)is composed of a major body-centered-cubic(bcc)phase with significant impurities,the bcc phase fraction increases with the C concentration and achieves almost 100%at x=20.Moreover,the increase of C content x results in an expansion of the bcc lattice,an enhancement of the microhardness,an increase in residual resistivity and a small variation of density of states at the Fermi level.All these features are consistent with the expectation that carbon atoms occupy the interstitial site.For x≥11.1,the X-ray photoelectron spectroscopy indicates the bond formation between the carbon and metal atoms,suggesting that some carbon atoms may also reside in the lattice site.In addition,a semiquantitative analysis shows that the enhanced mixing entropy caused by carbon addition plays a key role in stabilizing the(nearly)single solid-solution phase.Our study not only provides the first series of carbon interstitial HEAs with a bcc structure,but also helps to better understand the alloying behavior of carbon in refractory HEAs.展开更多
A functionalized single-walled carbon nanotube (SWCNT) of a finite length with a ring-like hydrogenation around its surface is designed toward fabrication of a molecular field-effect transistor (FET) device. The molec...A functionalized single-walled carbon nanotube (SWCNT) of a finite length with a ring-like hydrogenation around its surface is designed toward fabrication of a molecular field-effect transistor (FET) device. The molecular wire thus designed is equipped with a quantum dot inside, which is confirmed by theoretical analysis for electronic transport. In particular, the current-voltage (I-V) characteristics under influence of the gate voltage are discussed in detail.展开更多
文摘利用含时密度泛函(Time-Dependent Density Functional Theory,TDDFT)方法在6-311++g**基组水平上研究了外电场对碳原子线前十个激发态特性和能级分布的影响.结果表明不同大小、不同方向的电场对碳原子线激发态和能级分布影响各不相同.其中沿分子轴方向较高的电场对碳原子线能级影响较为明显,影响了电子在分子中的输运,从而对碳原子线伏安特性产生一定的影响.
文摘利用碳原子线(CAWs)上的羧基与2-巯基乙胺的氨基发生选择性缩合反应生成巯基化碳原子线,并用红外光谱对反应进程及一些反应条件的影响进行表征.实验结果表明:10 mg经浓硝酸氧化处理过的碳原子线在含有20 mg巯基乙胺、10 mL CH2Cl2、1 mL N(Et)3(三乙胺)、0.2 g DCC(二环己基碳化二亚胺)的液相反应体系中,60℃温度下作用24 h可完成缩合反应,生成巯基化碳原子线.在该巯基化过程中,CAWs的特征碳链结构并未发生可觉察的变化.
基金the foundation of Westlake University for financial supportThe work at Zhejiang University was supported by the National Key Research and Development Program of China(2017YFA0303002)。
文摘The introduction of carbon interstitials into high-entropy alloys(HEAs)provides an effective way to improve their properties.However,all such HEA systems explored so far are limited to those with the face-centered-cubic(fcc)structure.Here we report the structural,mechanical and physical properties of the refractory(Nb_(0.375)Ta_(0.25)Mo_(0.125)W_(0.125)Re_(0.125))_(100−x)C_(x) HEAs over a wide x range of 0≤x≤20.It is found that,whereas the starting HEA(x=0)is composed of a major body-centered-cubic(bcc)phase with significant impurities,the bcc phase fraction increases with the C concentration and achieves almost 100%at x=20.Moreover,the increase of C content x results in an expansion of the bcc lattice,an enhancement of the microhardness,an increase in residual resistivity and a small variation of density of states at the Fermi level.All these features are consistent with the expectation that carbon atoms occupy the interstitial site.For x≥11.1,the X-ray photoelectron spectroscopy indicates the bond formation between the carbon and metal atoms,suggesting that some carbon atoms may also reside in the lattice site.In addition,a semiquantitative analysis shows that the enhanced mixing entropy caused by carbon addition plays a key role in stabilizing the(nearly)single solid-solution phase.Our study not only provides the first series of carbon interstitial HEAs with a bcc structure,but also helps to better understand the alloying behavior of carbon in refractory HEAs.
文摘A functionalized single-walled carbon nanotube (SWCNT) of a finite length with a ring-like hydrogenation around its surface is designed toward fabrication of a molecular field-effect transistor (FET) device. The molecular wire thus designed is equipped with a quantum dot inside, which is confirmed by theoretical analysis for electronic transport. In particular, the current-voltage (I-V) characteristics under influence of the gate voltage are discussed in detail.
