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基于芯片级控温技术的玻尔兹曼常量测定仪 总被引:1,自引:0,他引:1
为解决测量玻尔兹曼常量时获取PN结真实温度及温度连续变化的问题,设计了基于芯片级控温技术的玻尔兹曼常量测定仪.该仪器采用以AVR单片机为核心控制系统,集成电路CA3046为控温芯片,24064图形点阵液晶显示器作为显示单元.将加热电阻和测温传感器与PN结集成在同一芯片内组成PN组件.单片机对PN组件进行温度控制,可以实现对PN组件中PN结温度调整、恒温控制、温度测量并用液晶屏24064显示.实际应用表明,该测定仪具有升降温快、控温稳定,测量结果与国际公认值相对偏差小于2%. 相似文献
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玻尔兹曼常数kB是物理学中的一个重要常数,它联系着微观粒子系统(如气体分子)的动能与系统温度之间的关系,所以它是原子、分子世界与宏观物质的性质(如压强、温度等)之间的桥樑。目前只有采用在氩气中测声速的方法能使KB。数值的测量达到百万分之二的精确度,一般将百万分之一的标准称为百万分率,简写为ppm。其他测量kB的方法,如测量电阻器中的噪声,测定气体中的介电常数和测量黑体辐射等都达不到ppm的标准。 相似文献
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采用基于延时分次扫描单光子计数器为探测装置的皮秒时间分辨荧光光谱测试系统研究了菠菜光系统(PSⅡ)核心复合物光能传递与温度的关系.分别对PSII核心复合物样品在20℃、42℃、48℃下做温浴处理,然后以脉宽为120 ps,重复率为4MHz,波长为514nm的Ar+激光作为光源分别激发处理后样品的荧光.通过对测量结果进行数据处理,分析比较发现:同一温度下,呈荧光带的激发能传递速度比副荧光带处的快;同一波长下,慢组分的时间常量随温度升高而变慢,而快速组分的时间常数则变化不大;做42℃温浴处理的样品接近于蛋白质解体的临界状态. 相似文献
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稀土荧光特性与温度关系 总被引:1,自引:0,他引:1
为研究稀土荧光特性与温度关系,从典型稀土材料的能级结构出发,根据激发态多能级间的玻尔兹曼热平衡分布理论,对激发态能级的粒子数分布情况与温度关系进行研究.发现随着温度的上升稀土发光荧光寿命变短,激发态高能级辐射荧光比例增大;而荧光强度由于受到非辐射跃迁系数和能量传递效率的双重影响将会呈现先上升后下降的变化.以钒磷酸钇铕Y(P,V)O4∶Eu3+荧光粉材料为例进行实验研究,测量了95K到510K温度范围内Y(P,V)O4∶Eu3+荧光材料在395nm紫外光激励下所发荧光的荧光寿命、荧光强度和荧光分支比随温度的变化规律,实验结果与理论相符合. 相似文献
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We investigate the influence of spontaneous symmetry breaking on the decoherence of a many-particle quantum system. This decoherence process is analyzed in an exactly solvable model system that is known to be representative of symmetry broken macroscopic systems in equilibrium. It is shown that spontaneous symmetry breaking imposes a fundamental limit to the time that a system can stay quantum coherent. This universal time scale is t(spon) approximately = 2piNH/(kBT), given in terms of the number of microscopic degrees of freedom N, temperature T, and the constants of Planck (h) and Boltzmann (kB). 相似文献
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Using molecular-dynamics simulation, we determine the magnitude and anisotropy of the kinetic coefficient (mu) for the crystal growth from the melt for the hard-sphere system through an analysis of equilibrium capillary fluctuations in interfacial height. We find mu100 = 1.44(7), mu110 = 1.10(5), and mu111 = 0.64(3) in units of square root (kB/(mTm)), where kB is Boltzmann's constant, m is the particle mass, and Tm is the melting temperature. These values are shown to be consistent, with some exceptions, with those obtained in recent simulation results a variety of fcc metals, when expressed in hard-sphere units. This suggests that the kinetic coefficient for fcc metals can be roughly estimated from C square root (R/(MTm)), where R is the gas constant, M is the molar mass, and C is a constant that varies with interfacial orientation. 相似文献
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Joachim Fischer 《Annalen der Physik》2019,531(5)
In November 2018, the four base units, kilogram, ampere, kelvin, and mole, of the International System of Units (SI) are redefined in terms of fundamental physical constants. The redefinition comes into force on World Metrology Day, 20 May 2019. The kelvin, the base unit of thermodynamic temperature, from then is to be founded on a fixed numerical value of the Boltzmann constant. Herein, the change in the definition of the kelvin and the consequences for practical temperature measurement are explained. The primary thermometry methods applied to determine the numerical value of the Boltzmann constant for the redefinition are reviewed. The prospects for the future application of these methods are outlined. 相似文献
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We report the first experimental evidence of nontrivial thermal behavior of the simplest mesoscopic system--a superconducting loop. By measuring the specific heat C of an array of 450,000 noninteracting aluminum loops with very high accuracy of approximately 20 fJ/K, we show that the loops go through a periodic sequence of phase transitions (with a period of an integer number of magnetic flux quanta) as the magnetic flux threading each loop is increased. The transitions are well described by the Ginzburg-Landau theory and are accompanied by discontinuities of C of only several thousands of Boltzmann constants kB. 相似文献
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Thermophoresis depletes DNA from a heated spot. We quantify for the first time the thermal diffusion constant D(T)=0.4x10(-8) cm(2)/s K for DNA, using fluorescent dyes and laser heating. For 5 kB DNA we extrapolate a 1000-fold depletion from a temperature difference of 50 K. Surprisingly, convection generated by the same heating can turn the depletion into trapping of DNA. Trapped DNA can form point geometries 20 microm in diameter with more than 1000-fold enhanced concentrations. The accumulation is driven only by temperature gradients and offers a new approach to biological microfluidics and replicating systems in prebiotic evolution. 相似文献
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《Comptes Rendus Physique》2009,10(9):835-848
There is currently great interest in the international metrology community for new accurate determinations of the Boltzmann constant k, with a view to a new definition of the unit of thermodynamic temperature, the kelvin. Indeed, k is related to the quantum of energy kT, where T is the thermodynamic temperature.The value of the Boltzmann constant can be obtained from measurements of the velocity of the sound in a noble gas. In the method described here, the experiment is performed in a closed spherical cavity. To obtain an accurate value for k, all the parameters of the experiment (gas purity, static pressure, temperature of the device, exact shape of the cavity, etc.) have to be carefully controlled. As correction terms have to be applied to the acoustic signals, the validity of the theoretical models from which they are derived is crucial.The new determination carried out at the LNE-INM/CNAM is based on the same principles as in the acoustic experiment of Moldover et al. at NIST in 1988, which led to the most accurate determination of the Boltzmann constant up to now. However, several fundamental modifications and improvements have been made in this new experiment to measure and control the parameters that set the measured value of k. To cite this article: L. Pitre et al., C. R. Physique 10 (2009). 相似文献
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介绍用硅三级管作为样品,在低温150K-250K范围内,测量其PN结正向特征,可精确求得玻耳兹曼常量及硅半导体材料禁带宽度的值。 相似文献
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介绍了PN结物理特性综合实验原理,利用绘图软件Matlab对实验数据进行曲线拟合,得到了PN结伏安特性函数表达式和PN结正向压降与温度间关系的拟合曲线,计算了常温下玻尔兹曼常数和PN结温度传感器灵敏度及T=0 K时的半导体近似禁带宽度。 相似文献
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Qing-Miao Meng Ji-Jian Jiang Jing-Lun Liu Zhong-Rang Li 《International Journal of Theoretical Physics》2010,49(8):1739-1745
Applying the entropy density near the event horizon, we obtained the result that the radiation energy flux of the black hole
is always proportional to the quartic of the temperature of its event horizon. That is to say, the thermal radiation of the
black hole always satisfies the generalized Stefan–Boltzmann law. The derived generalized Stefan–Boltzmann coefficient is
no longer a constant. When the cut-off distance and the thin film thickness are both fixed, it is a proportional coefficient
which is related to the black hole mass, the kinds of radiation particles and space–time metric near the event horizon. In
this paper, we have put forward a thermal particle model in curved space–time. By this model, the result has been obtained
that when the thin film thickness and the cut-off distance are both fixed, the radiation energy flux received by observer
far away from the Schwarzschild black hole is proportional to the average radial effusion velocity of the radiation particles
in the thin film, and inversely proportional to the square of the distance between the observer and the black hole. 相似文献
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A one-dimensional lattice-gas model is proposed and used to simulate diffusion processes in one dimension. Explicit forms of transport coefficients are given as a function of density and kinetic energy within the Boltzmann approximation. Without definitions of temperature and pressure, a steady nontrivial solution is given analytically in the nonconvective case when the kinetic energy is kept constant. 相似文献