Charles has spent most of his career working with home built mass spectrometry instrumentation. At the University of Central Arkansas, where he received a bachelor’s of science in chemistry, Charles investigated state-specific ion-neutral reactions using William S. Taylor’s selected-ion drift cell mass spectrometer. He went on to receive his Ph.D. in physical chemistry from JILA at the University of Colorado under advisors Veronica M. Bierbaum and W. Carl Lineberger. Charles’ thesis work was conducted using a Flowing Afterglow-Selected Ion Flow Tube (FA-SIFT) and a Negative Ion Photoelectron Spectrometer (NIPES). With the FA-SIFT, Charles measured kinetic rates and product distributions for ion-neutral reactions. The NIPES was used to measure the electron binding energies of anions. The complementary nature of these two experiments allow comprehensive thermochemical determination of hydrogen bond energies. To support his experimental work, Charles investigates thermochemistry, reaction dynamics, and mechanisms by performing electronic structure calculations. His thesis also focused on instrument development as he designed, constructed, and installed a working electrospray ionization source for the FA-SIFT. At Vanderbilt University, Charles investigates metabolomics problems using high-performance–liquid-chromatography ion-mobility mass spectrometry (HPLC-IMS-MS).