A new form of coherent 2D spectroscopy involving a pair of electronic resonances appears to provide several advantages over more established techniques. It can resolve congested peaks and sort them by vibrational quantum number, rotational quantum number, and isotopomer. The high degree of symmetry in the resulting spectra facilitates the ability to assign the quantum numbers and isotopomer for each peak. Quantitative results are demonstrated using an isotopomeric mixture of bromine.