Infrared spectroscopy of the v3 band of C3 in helium droplets

The C-3 molecule is an important species known to participate in key chemical reactions in combustion and astrochemistry. Its occurrence in environments of interest, its intramolecular physics, and its intermolecular reactivity have been areas of extensive and ongoing study. Much of the interest in C-3 is related to investigating its interactions with other species relevant to combustion processes or astrochemistry. Helium droplet methods offer a promising route to assemble and study a wide variety of novel complexes, clusters, and adducts made from C-3. Here we report the results of our recent efforts to dope cold helium droplets with C-3 molecules and record the rotationally-resolved infrared spectrum of the embedded C-3. The spectrum consists of P(2), R(0), and R(2) lines well-described by a linear rotor Hamiltonian with v(0) = 2039.09(2) cm(-1), B = 0.204(5) cm(-1), and T = 0.37 K. The B rotational constant of the C-3 molecule is found to be reduced from its gas-phase value by a factor of 2.1 due to rotational following by the helium solvent. (c) 2018 Author(s).