New measurements of differential cross-sections for excitation of the a 1 + g (v = 0, 1) state in molecular nitrogen reveal a cusp-like angular distribution. This feature is distinctly observed for the first time in the present electron energy-loss experiment as a result of finer scattering angle grid and impact energy coverage than previous measurements. This feature is similar to that observed in atomic targets such as He, Hg and Ba. The observed phenomenon suggests an interference effect related to configuration-interaction coupling between lower and excited states that are of the same symmetry. It is hoped that the present work will stimulate theoretical investigations into the physics that governs this cusp-like behaviour.(Some figures in this article are in colour only in the electronic version)Electron impact excitation of atomic and molecular targets is of continuing importance in our understanding of a host of natural and man-made phenomena, including aurora [1], airglow [2], plasma sterilization [3] and lighting technologies [4,5]. Considerable effort has been made in the past to both theoretically and experimentally determine electron scattering crosssections for these targets. Whereas significant progress has been made for atomic targets [5][6][7], particularly through benchmarking against distinguishing experimental features such as resonances [8,9] and electron impact coherence parameters [10,11], even homonuclear diatomic molecular targets (e.g., N 2 ) remain a significant challenge to theory. This difficulty is largely on account of their reduced symmetry and additional rotational and vibrational degrees of freedom in nuclear motion, which couple into the electronic motion. Distinct molecular features observed experimentally are necessary to test and refine different theoretical approaches to better understand and quantify electron interference effects. Moreover, both