Open AccessBehavior of excess electrons in supercritical fluids -- Electron attachment
Author(s) -
Masaru Nishikawa,
Richard A. Holroyd,
Kengo Itoh
Publication year - 1999
Language(s) - English
Resource type - Reports
DOI - 10.2172/354895
Subject(s) - supercritical fluid , electron , compressibility , chemistry , ion , electrostriction , volume (thermodynamics) , thermodynamics , analytical chemistry (journal) , materials science , physics , organic chemistry , chromatography , quantum mechanics , piezoelectricity , composite material
The behavior of excess electrons in supercritical ethane was investigated by measuring mobility and reaction rates. Mobilities wee measured by means of a time-of-flight method at 306--320 K as a function of pressure. Mobility values decreased at all temperatures with increasing pressure, but showed a small minimum or a shoulder at the pressure where the compressibility {chi}{sub T} has a peak. Electron attachment to CO{sub 2}, NO, pyrimidine and C{sub 2}F{sub 4} over the same temperature range was studied as a function of pressure. Both attachment rate constants k{sub a} for NO and C{sub 2}F{sub 4}, and equilibrium constants K({double_bond}k{sub a}/k{sub d}) for CO{sub 2} and pyrimidine increased sharply at pressures of {chi}{sub T} peaks. Activation volumes V{sub a}* and reaction volumes {Delta}V{sub r} are very large and negative in the critical region. The volume change is mainly due to electrostriction around ions formed. The results are compared to volume changes predicted by a compressible continuum model