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| 2. |
- Håkansson, Björn, et al.
(författare)
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Improved hot-wire procedure for thermophysical measurements under pressure
- 1988
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 59:10, s. 2269-2275
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Tidskriftsartikel (refereegranskat)abstract
- A new and simplified version of the circuitry for the transient hot‐wire method is presented. The circuitry provides a wide range of currents allowing probe wires of various diameters to be used in order to match the thermal properties of the specimen to be investigated. The analysis of the temperature increase during the heat pulse is based on the exact solution for a heated wire immersed in a medium. Data are corrected for varying power. The method was tested by computer simulations and by measurements of the thermal conductivity (λ) and the heat capacity per unit volume (ρcp ) of glycerol at room temperature and atmospheric pressure, and for CsCl and NaCl at room temperature and at pressures up to 2 GPa. The results on glycerol and CsCl are in excellent agreement with previous works. The inaccuracy in λ and ρcp is estimated as 1%–2% and 3%–5%, respectively, but the standard deviation of the measurements is as low as 0.2% for λ and 1% for ρcp. The improved procedure makes it possible to detect systematic errors caused by reflection of the heat pulse from the walls of the high‐pressure cell. This error, which reveals itself by a curvature of the residual, defined as the difference between fitted function and data, was demonstrated in the case of NaCl. A theoretical estimate of the influence of perturbations due to reflection was also carried out and it was found that the error mainly affects the value of ρcp.
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| 3. |
- Håkansson, Björn, et al.
(författare)
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Thermal conductivity and heat capacity of solid NaCl and NaI under pressure
- 1986
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 47:4, s. 355-362
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Tidskriftsartikel (refereegranskat)abstract
- We measured the thermal conductivity and heat capacity per unit volume for solid NaCl and NaI using the transient hot-wire technique. Measurements were performed in the temperature range 100–400 K and at pressures up to 2 GPa. Analysis of the thermal conductivity data showed that the Leibfried-Schlömann formula is a better description for NaCl than for NaI. For both NaCl and NaI the effect of optic phonons on thermal conductivity cannot be ignored. However, taking only acoustic phonons into account is a better approximation for NaI than for NaCl, due to the larger ionic mass ratio for NaI. The specific heat capacities, obtained at room temperature, were approximately independent of pressure.
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| 4. |
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| 5. |
- Jonsson, Gunnar, et al.
(författare)
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Compensation for Non-normal Ejection of Large Molecular Ions in Plasma Desorption Mass Spectrometry
- 1989
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 0951-4198 .- 1097-0231. ; 3:6, s. 190-191
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Tidskriftsartikel (refereegranskat)abstract
- By introducing an Einzel lens in the field-free region of a straight time-of-flight mass spectrometer, secondary ions of large mass can be detected more efficiently in plasma-desorption mass spectrometry. This procedure compensates for the large radial velocities of large molecular ions recently observed experimentally. It is shown that large molecular ions like those of lysozyme can now be detected more efficiently, and larger molecular ions than observed before in plasma-desorption mass spectrometry (like those of bovine ovalbumin, mol. wt 45 000) can now be studied.
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| 6. |
- Sigalas, I., et al.
(författare)
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Thermal conductivity and heat capacity of solid NaBr under pressure
- 1985
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Ingår i: International journal of thermophysics. - : Plenum Publishing. - 0195-928X .- 1572-9567. ; 6:2, s. 177-190
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Tidskriftsartikel (refereegranskat)abstract
- Using the transient hot-wire method, measurements were made for solid NaBr of both the thermal conductivity and the heat capacity per unit volume. The measurements were performed in the temperature range 100 to 400 K and at pressures up to 2 GPa. An adiabatic compression technique allowed the determination of the thermal expansivity as a function of pressure at room temperature. The heat capacity did not vary with pressure. Analysis of the thermal conductivity data showed that it can be described adequately by the Leibfried-Schlömann formula. For temperatures up to 400 K only acoustic modes needed to be taken into account. A small contribution of optic modes to the heat transport might be apparent at the highest temperatures.
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| 7. |
- Sigalas, I., et al.
(författare)
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Thermal conductivity of sodium halides under pressure
- 1986
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Ingår i: Physica B+C. - : Elsevier. - 0378-4363. ; 139-140, s. 165-167
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Tidskriftsartikel (refereegranskat)abstract
- Results for the thermal conductivity under pressure of the four Na-halides are presented and compared, and discussed using the Leibfried-Schlömann formula.
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