A dynamic Knudsen-effusion-torsion balance

In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au2 (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au2, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au2 with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol-1), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol-1 to the Au-Au bond7. So, as expected, in the specie with none unpaired electrons, the two 6s1 (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au2 with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au2 is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).

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The Torsion Balance Company

Analytical Chemistry ◽

10.1021/ac60276a827 ◽

1969 ◽

Vol 41 (7) ◽

pp. 120A-120A

Keyword(s):

Torsion Balance

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Study of thermal stability of n-type skutterudites Sr0.07Ba0.07Yb0.07Co4Sb12 by differential thermal analysis and Knudsen effusion method

Calphad ◽

10.1016/j.calphad.2021.102258 ◽

2021 ◽

Vol 73 ◽

pp. 102258

Author(s):

František Zelenka ◽

Jakub Strádal ◽

Pavel Brož ◽

Jan Vřešťál ◽

Jiří Buršík ◽

...

Keyword(s):

Thermal Stability ◽

Thermal Analysis ◽

Differential Thermal Analysis ◽

Knudsen Effusion ◽

Knudsen Effusion Method ◽

Effusion Method ◽

Thermal Stability Of

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Thermal Noise Decoupling of Micro-Newton Thrust Measured in a Torsion Balance

Symmetry ◽

10.3390/sym13081357 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1357

Author(s):

Linxiao Cong ◽

Jianchao Mu ◽

Qian Liu ◽

Hao Wang ◽

Linlin Wang ◽

...

Keyword(s):

Thermal Noise ◽

Rotation Axis ◽

Electrostatic Force ◽

Thermal Control ◽

Positive Temperature Coefficient ◽

Torsion Balance ◽

Positive Temperature ◽

Thermal Drift ◽

Low Thrust ◽

Z Domain

The space gravitational wave detection and drag free control requires the micro-thruster to have ultra-low thrust noise within 0.1 mHz–0.1 Hz, which brings a great challenge to calibration on the ground because it is impossible to shield any spurious couplings due to the asymmetry of torsion balance. Most thrusters dissipate heat during the test, making the rotation axis tilt and components undergo thermal drift, which is hysteretic and asymmetric for micro-Newton thrust measurement. With reference to LISA’s research and coming up with ideas inspired from proportional-integral-derivative (PID) control and multi-timescale (MTS), this paper proposes to expand the state space of temperature to be applied on the thrust prediction based on fine tree regression (FTR) and to subtract the thermal noise filtered by transfer function fitted with z-domain vector fitting (ZDVF). The results show that thrust variation of diurnal asymmetry in temperature is decoupled from 24 μN/Hz1/2 to 4.9 μN/Hz1/2 at 0.11 mHz. Additionally, 1 μN square wave modulation of electrostatic force is extracted from the ambiguous thermal drift background of positive temperature coefficient (PTC) heater. The PID-FTR validation is performed with experimental data in thermal noise decoupling, which can guide the design of thermal control and be extended to other physical quantities for noise decoupling.

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