Dissociative attachment reactions of electrons with gas phase superacids

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5636685

Liu, X

Using the flowing afterglow Langmuir probe (FALP) technique, dissociative attachment coefficients [beta] for reactions of electrons with gas phase superacids HCo(PF[sub 3])[sub 4], HRh(PF[sub 3])[sub 4] and carbonyl hydride complexes HMn(CO)[sub 5], HRe(CO)[sub 5] have been determined under thermal conditions over the approximate temperature range 300[approximately]550 K. The superacids react relatively slowly (<1/20 of [beta][sub max]) with free electrons in a thermal plasma, and the values of [beta] obtained this far do not show a correlation between acidity and [beta]. The pioneer researchers in this field had speculated that any superacid would be a rapid attacher of electrons; it was found that this speculation is not true in general. The product distribution of electron attachment reaction to HCo(PF[sub 3])[sub 4] was found to be independent of temperature even though the [beta][HCo(PF[sub 3])[sub 4]] increases with temperature. This proposes that the electron attachment process occurs well before the excited complex dissociates. In addition, the activation energy of HCo(PF[sub 3])[sub 4] for electron attachment has been derived from the Arrhenius plots. The carbonyl hydride complexes, HMn(CO)[sub 5] and HRe(CO)[sub 5], react relatively rapidly (>1/4 of [beta][sub max]) with free electrons in thermal plasma. This indicates that these reactions cannot be significantly endothermic. Observation of rapid attachment for these non-superacids shows that the Mn-CO and Re-CO bonds are weaker than the Mn-H and Re-H bonds, respectively. Comparisons between the carbonyl and trifluorophosphine cases implies that fast electron capture is related more to the CO ligand than to the transition-metal species.

• Research Organization: Oklahoma Univ., Norman, OK (United States)
• OSTI ID: 5636685
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical &amp; Physicochemical Properties
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700380* -- Elementary &amp; Classical Processes in Plasmas-- (1992-)
ACTIVATION ENERGY
CAPTURE
CARBONYLS
CHEMICAL REACTION KINETICS
COBALT COMPOUNDS
ELECTRIC PROBES
ELECTRON ATTACHMENT
ELECTRON CAPTURE
ENERGY
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
INORGANIC ACIDS
KINETICS
LANGMUIR PROBE
PHOSPHORUS COMPOUNDS
PHOSPHORUS FLUORIDES
PLASMA
PROBES
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
RHENIUM COMPOUNDS
RHODIUM COMPOUNDS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENT COMPOUNDS