Anomalous photoinduced absorption of conjugated polymer/fullerene mixtures at low temperatures and high frequencies

2004 ◽  
Vol 141 (1-2) ◽  
pp. 109-112 ◽  
Author(s):  
M.C Scharber ◽  
C Winder ◽  
H Neugebauer ◽  
N.S Sariciftci
Keyword(s):  
Low Temperatures ◽  
Conjugated Polymer ◽  
Photoinduced Absorption ◽  
High Frequencies

The anomalous skin effect

1952 ◽  
Vol 215 (1123) ◽  
pp. 481-497 ◽  
Keyword(s):  
Free Path ◽  
Low Temperatures ◽  
Skin Effect ◽  
Mean Free Path ◽  
Skin Depth ◽  
Surface Conductance ◽  
High Frequencies ◽  
Surface Imperfections ◽  
Anomalous Skin Effect ◽  
Cadmium Lead

The anomalous skin effect arises in good conductors at low temperatures and high frequencies when the electronic mean free path becomes comparable with or greater than the classically calculated skin depth. Measurements have been made on a number of metals at frequencies of 1200 and 3600 Mc/s, and the form of variation of r. f. surface conductance with d. c. conductivity agrees well with that predicted theoretically by Reuter & Sondheimer, assuming that the electrons are scattered diffusely when they hit the surface of the metal. From the results, estimates are made of the effective value of σ/ l , the ratio of d. c. conductivity to mean free path, and hence of the free surface area of the occupied region of k -space. The estimate for copper agrees well with that expected theoretically; those for silver and gold are rather lower than the theoretical values. For the other metals investigated, tin, cadmium, lead and aluminium, no theoretical estimates are available. The results are very sensitive to the presence of surface imperfections; the effect of these is discussed.

scholarly journals Review of the Effects of the Influence of External Vibrations on the Freezing Point of Water

2020 ◽  
Vol 320 ◽  
pp. 00032
Author(s):  
Emmanuele Adorni ◽  
Mikhail Ivanov ◽  
Roberto Revetria
Keyword(s):  
Liquid State ◽  
High Frequency ◽  
Low Temperatures ◽  
Freezing Point ◽  
Tap Water ◽  
Distilled Water ◽  
High Frequencies ◽  
High Frequency Vibrations

With this paper we want to provide a first glance at some of those researches that studied how to lower the freezing point of water below the ordinarily point by using external vibrations. All the researches started with experiments on distilled water (obtained with different methodology depending on the experiment) and then moving forward to experiments on tap water (contaminated with a known amount of substances). In all cases, methods to bring the samples to an undercooled state were applied at first. Through high frequency vibrations it has been studied how the formation of ice in a vessel of water can be controlled mainly thanks to the development of the phenomenon of cavitation in the water. By increasing the pressure in certain zones of the samples it was possible to study the phenomena linked to water freezing. Some experiments showed how, even with high frequencies, it is still difficult to obtain reliable results on the topic of keeping the water in a liquid state in conditions of low temperatures and with vibrations applied to the fluid.

Dielectric Properties of Pd/Y8Z Composites

1999 ◽  
Vol 575 ◽  
Author(s):  
Mark G.H.M. Hendriks ◽  
Henk Verwei ◽  
Manon P. Timmerman
Keyword(s):  
Dielectric Properties ◽  
Percolation Threshold ◽  
Double Layer ◽  
Low Temperatures ◽  
Room Temperature ◽  
Electronic Conductivity ◽  
Impedance Measurements ◽  
High Frequencies ◽  
A Value ◽  
Double Layer Capacity

ABSTRACTImpedance measurements are performed on Pd/Y8Z composites. At 500 'C a 2- 108 times enhancement of the permittivity of the composite at a Pd composition near the percolation threshold for electronic conductivity relative to Y8Z at room temperature is obtained. At high frequencies, the enhancement decreases to a value comparable to geometric capacity of the composite as the double-layer capacity diminishes. At relatively low temperatures the capacity of Y8Z, due to ionic polarisability, increases with temperature.

AC Conductivity of Crystalline Materials and Glasses Ascribed to ADWPs

1995 ◽  
Vol 411 ◽  
Author(s):  
A. S. Nowick ◽  
A. V. Vaysleyb ◽  
H. Jain ◽  
X. Lu
Keyword(s):  
Frequency Dependence ◽  
Low Temperatures ◽  
Composition Dependence ◽  
Minimum Energy ◽  
Alkali Concentration ◽  
Loss Peak ◽  
Broad Distribution ◽  
Crystalline Materials ◽  
High Frequencies ◽  
Nearly Constant Loss

ABSTRACTThe behavior of the frequency dependence of the conductivity, σ(ω), of numerous crystalline materials and glasses is close to an ω1.0 dependence in the limit of low temperatures and/or high frequencies (referred to as the “nearly constant loss”, or NCL, regime). Detailed analysis of this behavior, including the frequency dependence of both ε′ and ε″, shows that it can be described phenomenologically as produced by a broad distribution of asymmetric double-well potentials (ADWPs) with low activation energies. In order to obtain an understanding of the atomic origins of such potentials, we investigate the composition dependence of this behavior in such materials as crystalline CeO2:1%Y3+ ceramics with variable [Y3+] and alkali germanate glasses with variable alkali concentration. The appearance of a discrete loss peak in CeO2: 1%Y3+ helps us understand the ADWPs as due to “off-symmetry” configurations that undergo wiggling motion between adjacent minimum-energy positions.

DIELECTRIC RELAXATION IN LIQUIDS: II. ISOMERIC PENTANEDIOLS

1961 ◽  
Vol 39 (11) ◽  
pp. 2139-2154 ◽  
Author(s):  
D. W. Davidson
Keyword(s):  
Hydrogen Bonding ◽  
High Frequency ◽  
Low Temperatures ◽  
Dipole Moments ◽  
Frequency Dispersion ◽  
Liquid Structure ◽  
Dielectric Constants ◽  
Oh Groups ◽  
High Frequencies ◽  
Static Dielectric Constants

For five pentanediols the infrared spectra, the dipole moments, and the static dielectric constants show an increasing degree of internal hydrogen bonding with increasing proximity of the OH groups. The dielectric dispersion loci at low temperatures are skewed arcs over most of the dispersion range. Values of the parameter β decrease from ca. 1 to 0.55 in the series 1,5-, 1,4-, 1,2-, 2,4-, and 2,3-pentanediol, which is also the order of increasing relaxation time τ0 at low temperatures. Increased τ0 is associated with increased irregularity of intermolecular hydrogen bonding, an effect which supports the view that relaxation proceeds by a co-operative mechanism which is facilitated by regularity in the liquid structure. At temperatures of "structural relaxation", values of log τ0 are linear in (T–T∞)−1; the proportionality constants, but not the T∞'s, are the same for all five diols.The experimental behavior at relatively high frequencies departs from both the skewed-arc and Glarum equations, although less from the latter. These departures are compared with the high frequency dispersion regions in n-propanol.

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