Interstellar C₆₀

Since fullerene was first discovered in1985, scientist find that fullerene has many excellent properties. Fullerene is another allotrope of carbon, this attracts more and more people to understand it. And a new branch of fullerenes is established. Until now, fullerene has been widely used in various fields, such as physics, chemistry, astronomy, life science and medicine, has showed a huge potential application prospect.Fullerenes are cage-like molecules of pure carbon, such as C6o, C70, C76, and C84. C60, also known as buckminsterfullerene, is the most stable fullerene and has a soccer-ball like structure. The presence of fullerenes in space has been suggested and observationally explored since their first synthesis in the laboratory in1985by Harry Kroto and his colleagues which earned them the1996Nobel prize in chemistry.C60(as well as C70) has recently been detected in reflection nebulae, post-asymptotic giant branch (AGB) stars, pre-planetary nebulae, planetary nebulae, Herbig Ae/Be stars, and young stellar objects through their characteristic infrared emission bands.The formation of C60in interstellar and circumstellar environments is not firmly established. Experimental studies have shown that C60can be made by gas-phase condensation (e.g. through vaporization of graphite) in a hydrogen-poor environment. In view of the simultaneous detection of C60and polycyclic aromatic hydrocarbon (PAH) molecules in hydrogen-rich interstellar and circumstellar regions, it has also been suggested that C60could be generated by the decomposition of hydrogenated amorphous carbon, or the destruction of PAHs, both induced by shocks and/or ultraviolet photoprocessing.The phase (gas or solid) and excitation mechanism of C60in interstellar and circumstellar conditions are also hotly debated in the literature. One model suggests that C60is attached to dust and emits in solid-phase at the equilibrium temperature of the dust. Another model suggests that C60is stochastically excited by ultraviolet photons and emits in the gas-phase. We prefer the latter model as in interstellar and circumstellar conditions the energy content of a C60molecule is often smaller than the energy of a single starlight photon and C60is expected to undergo stochastical heating.In chatper1, we first introduce the backgroud of fullerenes in the space and give various of method to obtain fullerenes. In chapter2, we detailedly represtent the physical properties, chemical properties, optical properties and thermal properties, and stability. In chapter3, we outline the observation and study of interstellar dust, and analyze the discovery of C6o in early interstellar:planetary nebula Tcl and reflection nebula NGC7023, and observation of interstellar space in last three years. In chapter4, we discuss the formation of C60molecules in interstellar and interstellar C60molecule excitation mechanism. In chapter5, we make a summary for all the works, and we also give the future investigation of fullerenes.