Laser-aided synthesis of fullerenes: a control and optimization standpoint

The feasibility of the large-scale production of a remarkable family of nanomaterials, denoted by fullerenes, is of vital importance for many scientific areas and is currently a challenging task. In this paper, a basic concept of the control system of fullerene synthesis by lasers is proposed. The designed algorithm links fullerene yield and production rate to laser characteristics. To consider the possibility of realizing the more efficient production of selective fullerenes such as C₆₀, expert knowledge on possible plasma regions within which fullerenes are synthesizing is suggested to determine the necessary local conditions for fullerene formation. The inverse control strategy based upon a structured neural network is employed to acquire and represent the knowledge, that is, the ultrafast and highly complex dynamics of processes evolving at the very short time-scale (10^-6-10^-8 s) in the laser-produced plasma. The optimized plasma zones providing a C₆₀ yield of 70% and production rate of 5.14 g/min (P_He = 240 Torr, power density = 7×10⁹ W cm^-2, T = 2700 K) from a graphite target are identified and displayed as time-dependent response.