I presently carry out experiments on electron attachment to molecules and thermal electron detachment from negative ions.  Rate coefficients for these reactions are measured using a flowing-afterglow Langmuir-probe (FALP) apparatus at thermal energies (295-675 K).  One valuable feature of cases in which a molecule attaches electrons to form the parent negative ion is that thermodynamics allows an accurate determination of the electron affinity of the subject molecule.  In some cases, e.g., octafluorocyclobutane, the electron affinity cannot be measured by inherently more accurate photodetachment because the ground states of the negative ion and the neutral have minimal Franck-Condon overlap.  
 
The same FALP apparatus is also used to study the neutralization of positive ions by negative ions.  This process is the reaction that limits the charge density in plasmas devoid of free electrons.  The database of neutralization reactions between molecular ions has proven helpful to persons modeling air plasmas.  We have found that neutralization reaction between atomic ions cover a far wider range of rate coefficient -- orders of magnitude -- which makes them more intriguing.  We collaborate with theorists to obtain a detailed understanding of the process for those reactions amenable to quantum theory (the fewest valence electrons, the better).  
 
In addition to the FALP apparatus, the laboratory has a high-temperature version which is used to study reactions to temperatures over 1000 K.  The HT-FALP has a practical limitation in that plasma diffusion to the walls of the apparatus increases with temperature, which makes ion-ion neutralization experiments more difficult.  
 
In the years around 2000, I was operating atmospheric-sampling instruments on NASA flights.  The most interesting was a flight in the stratosphere over Iceland, inadvertently passing through a volcanic plume (Hekla eruption, 2000).  It was the first time that a heavily-instrumented flight passed through a volcanic plume.  My sulfur dioxide readings went through the roof.  Those data were used in a NASA report on the subsequent engine damage from the ash.  I am a coauthor on three publications in volcano journals but can't claim to be an expert on the subject.
 
For 32 years I have maintained two tables in the Handbook of Chemistry and Physics: "Polarizabilities of Atoms and Molecules" and "Electron Affinites."  The former is an outgrowth of atomic and molecular beam measurements of static electric polarizabilities I carried out at New York University with Benjamin Bederson.  The latter was inspired by measurements I made at the University of Colorado with Carl Lineberger.  The updates to the tables are an unpaid task viewed as a service to the research community.  The tables focus on experimental values because when originally begun there were few reliable theoretical results.  That has greatly changed over the years, along with the volume of literature, but the tables still emphasize experimental values.