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Title: Study of the motion of electrons in non polar classical liquids. Measurement of Hall effect and f. i. r. search for low energy traps. Progress report

Abstract

Progress is reported on experiments aimed at the measurement of the Hall mobility of injected electrons in classical non polar insulating liquids and the optical absorption associated with electrons captured by shallow traps in the liquefied rare gases. Theoretical work aimed at a better understanding of the trapping kinetics of electrons by SF/sub 6/ and O/sub 2/ dissolved in rare gas liquids was also carried out. Its conclusion is that the electric field dependence of the trapping probability can be explained, basically without adjustable parameters, by considering the Poole-Frenkel-Schotky ionization of the excited state of the traps. From the analysis of published data on the motion of electrons in liquid ethane it is tentatively concluded that at low temperatures the trapping of electrons in the liquid involves a Jahn-Teller like distortion of a single ethane molecule while at higher temperatures it is necessary to consider a small molecular cluster, possibly made up of 2 molecules.

Publication Date:
Research Org.:
Purdue Univ., Lafayette, IN (USA)
OSTI Identifier:
6613729
Alternate Identifier(s):
OSTI ID: 6613729
Report Number(s):
DOE/ER/10375-T1
TRN: 81-008032
DOE Contract Number:
AS02-79ER10375
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; LIQUIDS; HALL EFFECT; ELECTRICAL INSULATORS; JAHN-TELLER EFFECT; RARE GASES; SULFUR FLUORIDES; TEMPERATURE DEPENDENCE; TRAPPING; ELECTRICAL EQUIPMENT; ELEMENTS; EQUIPMENT; FLUIDS; FLUORIDES; FLUORINE COMPOUNDS; GASES; HALIDES; HALOGEN COMPOUNDS; NONMETALS; SULFUR COMPOUNDS 656000* -- Condensed Matter Physics

Citation Formats

Not Available. Study of the motion of electrons in non polar classical liquids. Measurement of Hall effect and f. i. r. search for low energy traps. Progress report. United States: N. p., 1981. Web. doi:10.2172/6613729.
Not Available. Study of the motion of electrons in non polar classical liquids. Measurement of Hall effect and f. i. r. search for low energy traps. Progress report. United States. doi:10.2172/6613729.
Not Available. Tue . "Study of the motion of electrons in non polar classical liquids. Measurement of Hall effect and f. i. r. search for low energy traps. Progress report". United States. doi:10.2172/6613729. https://www.osti.gov/servlets/purl/6613729.
@article{osti_6613729,
title = {Study of the motion of electrons in non polar classical liquids. Measurement of Hall effect and f. i. r. search for low energy traps. Progress report},
author = {Not Available},
abstractNote = {Progress is reported on experiments aimed at the measurement of the Hall mobility of injected electrons in classical non polar insulating liquids and the optical absorption associated with electrons captured by shallow traps in the liquefied rare gases. Theoretical work aimed at a better understanding of the trapping kinetics of electrons by SF/sub 6/ and O/sub 2/ dissolved in rare gas liquids was also carried out. Its conclusion is that the electric field dependence of the trapping probability can be explained, basically without adjustable parameters, by considering the Poole-Frenkel-Schotky ionization of the excited state of the traps. From the analysis of published data on the motion of electrons in liquid ethane it is tentatively concluded that at low temperatures the trapping of electrons in the liquid involves a Jahn-Teller like distortion of a single ethane molecule while at higher temperatures it is necessary to consider a small molecular cluster, possibly made up of 2 molecules.},
doi = {10.2172/6613729},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 10 00:00:00 EST 1981},
month = {Tue Mar 10 00:00:00 EST 1981}
}

Technical Report:

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  • Important steps in our research were attained with the reliable room temperature measurement of the Hall mobility of injected electrons in tetramethyl silane. We calculated the distribution of fluctuation of the conduction band minimum. Its rms value is in good agreement with our previous evaluation based on a different approach. This gives us confidence on other aspects of our calculations to describe the motion of electrons in non polar liquids.
  • During the last year the first measurements were obtained of the Hall mobility of electrons injected in an insulating non polar liquid (tetramethyl silane). The resulting Hall mobility appears to be approx. 10% higher than the drift mobility measured on the same sample. We are completing a data acquisition system to be able to correct for several experimental errors that became apparent due, e.g., to the random fluctuations of accelerator current, the nonhomogeneity of the applied electric fields, etc. Theoretical work aimed at the understanding of the observed electric field induced increase of the electron capture rate constant by N/submore » 2/O dissolved in Ar and Xe was carried out. Similarly to the conclusions reached in the case of O/sub 2/ and SF/sub 6/ the Stark effect is responsible for the electric field induced changes of the capture probability. Finally a large portion of the equipment necessary for the f.i.r. photoconductivity experiment was constructed. During its testing it became obvious that changes of design were needed because the major source of noise is not expected to be detector noise but instead, shot noise associated with the main electron current.« less
  • Research is reported on electron mobility in organic liquids, Hall mobility of electrons injected in liquid argon, photoconductivity of trapped electrons in argon, and magneto-photoemission into rare gases. (GHT)
  • Our research on the motion of electrons in insulating liquids has had both a theoretical and an experimental facet. The former was necessary to guide the latter. The experimental aims of the program were to develop a new technique to measure the Hall mobility of injected electrons in an insulating liquid and to develop a measurement of the density of localized states within a few kT from the conduction band edge. On the basis of our theoretical work, we concluded that these states are essential for the understanding of phenomena involved in large part of the observations carried out inmore » studying the motion of electrons in liquids. The measurement of the hall mobility of electrons injected in liquids was very successful. Results from these experiments confirmed the expected importance of localized states in the liquid. We were however, unable to directly measure the density of localized states below the conduction band edge of rare gasses. Our theoretical work was able to explain the apparent saturation of the time of flight (TOF) velocity in rare gasses, the increase of the saturation TOF velocity by the addition of impurities to rare gasses as well as the electric field induced variation of the probability of capture of an electron by an impurity. An estimate of the average energy of localized states below the conduction band edge was calculated. A novel method for the measurement of the effective mass of electrons injected in an insulating liquid was proposed. Finally an adaptation of the theory of the mobility of electrons scattered by phonons that has been used for solids was adapted to liquids.« less