Relaxation oscillations between Marangoni cells and double diffusive fingers in a reactive liquid-liquid system

► We report on a novel kind of coupling between Marangoni- and double-diffusive finger convection. ► This coupling occurs in the form of relaxation oscillations. ► The presence of density gradients influences the characteristics of the substructured Marangoni convection. ► This affects both the lifetime of the Marangoni convection and the regeneration of the Marangoni driving force. ► With these results, a better understanding of aspects of interfacial turbulence is possible.