相关实验视频
Updated: Jul 13, 2026

05:20
Characterization of Thermal Transport in One-dimensional Solid Materials
Published on: January 26, 2014
在石墨烯中的室温量子霍尔效应.
K S Novoselov1, Z Jiang, Y Zhang
1Department of Physics, University of Manchester, Manchester M13 9PL, UK.
概括
研究人员在室温下在石墨烯中展示了量子霍尔效应,克服了极低温度的先前限制. 这一突破使量子霍尔电阻标准能够得到更广泛的访问.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 量子力学就是量子力学.
- 材料科学是一种材料科学.
背景情况:
- 量子霍尔效应 (QHE) 是一个宏观的量子现象,对于理解量子物理学至关重要.
- QHE导致了量子电阻标准的发展.
- 从历史上看,QHE仅限于冷 (液) 温度.
研究的目的:
- 为了研究在室温下观察量子霍尔效应的可能性.
- 探索石墨烯在QHE测量中克服温度限制的潜力.
- 评估使QHE抗性标准更广泛地可访问的可行性.
主要方法:
- 在QHE实验中使用单层石墨烯 (2D材料).
- 在允许室温操作的条件下进行测量.
- 在指定的材料和温度范围内可靠地测量量子霍尔效应.
主要成果:
- 量子霍尔效应可靠地在室温下在石墨烯中测量.
- 这一成就消除了以前QHE观测所需的极端冷却的需要.
- 证明了QHE在环境温度下实际应用的潜力.
结论:
- 石墨烯使人们能够在室温下观察量子霍尔效应,这是一个显著的进步.
- 这一发现为基于QHE的抗性标准的广泛采用铺平了道路.
- 这项研究将量子计量学的可访问性扩大到专业实验室之外.
相关概念视频
Specific Heat
The specific heat capacity of a substance refers to the energy required to increase the temperature of one gram of that substance by one degree Celcius. Specific heat capacity is often represented in calories (cal), grams (g), and degrees Celsius (oC), but can also be expressed in joules (J), kilograms (kg), and Kelvin (K), among other units.
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or 4186 J/kg/K.
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or 4186 J/kg/K.
Le Chatelier's Principle: Changing Temperature
Consistent with the law of mass action, an equilibrium stressed by a change in concentration will shift to re-establish equilibrium without any change in the value of the equilibrium constant, K. When an equilibrium shifts in response to a temperature change, however, it is re-established with a different relative composition that exhibits a different value for the equilibrium constant.
To understand this phenomenon, consider the elementary reaction:
To understand this phenomenon, consider the elementary reaction:
Entropy
Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...
Effects of Temperature on Free Energy
The spontaneity of a process depends upon the temperature of the system. Phase transitions, for example, will proceed spontaneously in one direction or the other depending upon the temperature of the substance in question. Likewise, some chemical reactions can also exhibit temperature-dependent spontaneities. To illustrate this concept, the equation relating free energy change to the enthalpy and entropy changes for the process is considered:
Effect of Temperature Change on Reaction Rate
The Arrhenius equation,
Atomic Spectroscopy: Effects of Temperature
Atomization, converting samples into gas-phase atoms and ions, is essential for atomic spectroscopy. The flame temperature required for atomization affects the efficiency of the atomic spectroscopic methods by increasing the atomization efficiency and the relative population of the excited and ground states.
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...

