Abstract：

　　Alkyl radicals are important intermediates in hydrocarbon combustion. The ultraviolet (UV) photodissociation dynamics of a series of prototypical alkyl radicals (ethyl, propyl, butyl, pentyl, and cyclohexyl) via their Rydberg states have been investigated.  The UV photodissociation of primary alkyl radicals (ethyl, n-propyl, n-butyl, n-pentyl) via the 3s Rydberg state produce the H + alkene fragments with bimodal profiles in the translational energy and angular distributions, with a slow and isotropic and a fast and anisotropic component.  The UV photodissociation of secondary alkyl radicals (i-propyl and s-butyl) via the 3p Rydberg states and tertiary alkyl radical (t-butyl) via the 3d Rydberg states are also examined.  The product translational energy releases in these systems are also bimodal, while their angular distributions are nearly isotropic.  The bimodal distributions indicate two different dissociation pathways.  The slow and isotropic component corresponds to unimolecular dissociation of the hot radical after internal conversion from the Rydberg states to the ground state.  The fast component corresponds to a rapid, repulsive H-atom dissociation directly connected from the Rydberg states.  The photodissociation mechanisms and the possible role of conical intersections will be discussed.

报告人简介：

　　张劲松教授于1987年获得中国科学技术大学化学物理学学士学位，并于1993年获得加州大学伯克利分校化学博士学位。 1993-1996年任南加州大学博士后研究员。 1996年，他是加州大学河滨分校的化学助理教授和助理研究化学家。 他目前是加州大学河滨分校的化学系教授和研究学者。 他的研究兴趣主要包括自由基的光谱学和光化学，大气化学和测量以及燃烧化学。