Far-Infrared Absorption in Bulk Samples of Superconducting d-h.c.p. Lanthanum

1972 ◽  
Vol 50 (20) ◽  
pp. 2549-2551
Author(s):  
L. W. Kry ◽  
D. Hemming
Keyword(s):  
Infrared Absorption ◽  
Far Infrared ◽  
A Value ◽  
Gap Width ◽  
Absorption Measurements

Far-infrared absorption measurements have been made on bulk samples of d-h.c.p. lanthanum and the results indicate a gap width, 2Δ, of 11.6 ± 0.3 cm−1 or 1.44 ± 0.04 meV. Using a value of Tc = 4.87 ± 0.02 °K, taken from the literature, this gives 2Δ = (3.43 ± 0.09)kTc.

Far-infrared absorption in bulk samples of superconducting niobium and tantalum

1970 ◽  
Vol 48 (10) ◽  
pp. 1254-1258 ◽  
Author(s):  
D. Hemming ◽  
R. Sati ◽  
J. D. Leslie
Keyword(s):  
Critical Temperature ◽  
Infrared Absorption ◽  
Far Infrared ◽  
Gap Width ◽  
Absorption Measurements ◽  
Good Agreement

Measurements have been made of far-infrared absorption in bulk samples of superconducting niobium and tantalum at 1.41 °K. The results indicate a gap width 2Δ of 23.8 ± 0.2 cm−1 for niobium and 10.3 ± 0.2 cm−1 for tantalum. The measured values of the critical temperature, Tc, for these samples are 9.38 ± 0.04 °K for niobium and 4.33 ± 0.02 °K for tantalum. In terms of these values of Tc, 2Δ is 3.66 ± 0.05 kTc for niobium and 3.43 ± 0.08 kTc for tantalum. These values of 2Δ are in good agreement with those obtained by other methods, unlike earlier far-infrared absorption measurements on bulk niobium and tantalum that indicated anomalously low values of 2Δ.

High-pressure far-infrared absorption measurements on La1−xCaxMnO3−δ by means of synchrotron radiation

2006 ◽  
Vol 49 (1-2) ◽  
pp. 92-95
Author(s):  
A. Sacchetti ◽  
M. Cestelli Guidi ◽  
E. Arcangeletti ◽  
P. Postorino ◽  
A. Nucara ◽  
...  
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Infrared Absorption ◽  
Far Infrared ◽  
Absorption Measurements

Far-Infrared Absorption Measurements of Polypeptides and Cytochromecby THz Radiation

2002 ◽  
Vol 75 (5) ◽  
pp. 1083-1092 ◽  
Author(s):  
Kohji Yamamoto ◽  
Keisuke Tominaga ◽  
Hiroaki Sasakawa ◽  
Atsuo Tamura ◽  
Hidetoshi Murakami ◽  
...  
Keyword(s):  
Infrared Absorption ◽  
Far Infrared ◽  
Thz Radiation ◽  
Absorption Measurements

Structure of Alkali Metal-Catalyzed Butadiene Polymers

1953 ◽  
Vol 26 (3) ◽  
pp. 522-527
Author(s):  
A. W. Meyer ◽  
R. R. Hampton ◽  
J. A. Davison
Keyword(s):  
Transition Temperature ◽  
Alkali Metal ◽  
Infrared Absorption ◽  
Styrene Copolymers ◽  
A Value ◽  
Second Order Transition ◽  
Metal Catalyzed ◽  
Sodium And Potassium ◽  
Absorption Measurements ◽  
Butadiene Styrene

Abstract The structures of various sodium and potassium-catalyzed butadiene polymers were determined from infrared absorption measurements. All of the polymers had a higher proportion of butadiene in the 1,2-configuration (45–80 per cent) than emulsion polybutadiene (18–23 per cent). Polybutadienes catalyzed by potassium had 15–20 per cent less butadiene in the 1,2-configuration than those in which sodium was the catalyst. When a mixture of sodium and potassium was used, the results were nearly the same as with the potassium catalyst alone. Polybutadienes made at 5° had 10 to 15 per cent more butadiene in the 1,2-configuration than those made at 45°. Diluent type had little or no effect on the structure of the polybutadienes. The butadiene portions of butadiene-styrene copolymers were found to have the same relative proportions of 1,2-, cis-1,4- and trans-1,4-configurations as the butadiene homopolymers. The second order transition temperature of sodium-catalyzed polybutadiene polymerized at 30° was −45°, whereas the 75° polybutadiene had a value of −64°.

Quantitative Infrared Absorption Measurements on Tri-n-Butyl Phosphate

1980 ◽  
Vol 34 (4) ◽  
pp. 415-417 ◽  
Author(s):  
Vincent P. Tomaselli ◽  
Hassan Zarrabi ◽  
K. D. Möller
Keyword(s):  
Infrared Absorption ◽  
Molar Absorptivity ◽  
Measured Data ◽  
Pure Liquid ◽  
Absorption Bands ◽  
A Value ◽  
Self Association ◽  
Solvent Molecules ◽  
Infrared Absorption Bands ◽  
Absorption Measurements

The molar absorptivity, ε(ν̄) of three intense infrared absorption bands in tri- n-butyl phosphate has been measured as a function of concentration. For all three bands, ε(ν̄) is independent of concentration for dilute solutions, then decreases uniformly with increasing concentration, and finally becomes independent of concentration again as one approaches the pure liquid. A saturation effect is found at about 1.0 M for all cases. Deviations from Beer's law behavior are observed at concentrations which depend upon the absorption band and/or the choice of nonpolar solvent. Self-association of the solute molecules is considered to be the cause of the decrease in ε(ν̄) with increasing concentration. From the measured data, it is possible to estimate the number of solvent molecules required to prevent this self-association. For CCl4, we find this value to be 25 molecules of solvent per solute molecule, a value in agreement with elementary geometric consideration.

Temperature and Frequency Dependence of the Infrared Absorption in Three Kinds of Bi-Based Compounds

1992 ◽  
Vol 275 ◽  
Author(s):  
Y. Hayashi ◽  
Y. Harada ◽  
H. Sasakura ◽  
M. Nagayama
Keyword(s):  
Absorption Band ◽  
Infrared Absorption ◽  
Far Infrared ◽  
Infrared Region ◽  
Free Carrier Absorption ◽  
Phonon Modes ◽  
Superconducting Compounds ◽  
Carrier Absorption ◽  
Absorption Measurements ◽  
Made In

ABSTRACTInfrared absorption measurements have been made in three kinds of Bi compounds of a high-Tc family mainly by making use of powdered samples. Two of them are superconductors with Tc's of 108 K and 82 K, respectively, and the remaining one is a semiconductor. In each of the superconducting compounds, there appears Mid-Infrared absorption band: No such absorption band is found in the semiconducting compound. At Far-Infrared region, many absorption peaks due to phonons are clearly detected in all of these samples. Some of the phonon modes have been identified. At very low energy region, free carrier absorption appears in superconductors. Only this part of the absorption shows a temperature dependence. Absorption intensity decreases as the temperature decreases.

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