Evidence of an Equimolar C2H2–CO2 Reaction in the Synthesis of Carbon NanotubesThe work in Lausanne was supported by the Swiss National Science Foundation and its NCCR “Nanoscale Science”. We are also grateful to the Centre Interdisciplinaire de Microscopie Electronique (CIME) at EPFL for access to electron microscopes and for technical support. The authors acknowledge the support of INTAS 03-50-4409 grant.