Chemical dynamics of triacetylene formation and implications to the synthesis of polyynes in Titan's atmosphere

被引:39
作者
Gu, X. [1 ]
Kim, Y. S. [1 ]
Kaiser, R. I. [1 ]
Mebel, A. M. [2 ]
Liang, M. C. [3 ,4 ,5 ]
Yung, Y. L. [6 ]
机构
[1] Univ Hawaii Manoa, Dept Chem, Honolulu, HI 96822 USA
[2] Florida Int Univ, Dept Chem & Biochem, Miami, FL 33199 USA
[3] Acad Sinica, Res Ctr Environm Changes, Taipei 115, Taiwan
[4] Natl Cent Univ, Grad Inst Astron, Jhongli 320, Taiwan
[5] Acad Sinica, Inst Astron & Astrophys, Taipei 10617, Taiwan
[6] CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA
基金
美国国家科学基金会;
关键词
electronic structure calculations; planetary chemistry; crossed molecular beams; photochemical model; QUADRATIC CONFIGURATION-INTERACTION; NEUTRAL-NEUTRAL REACTIONS; COUPLED-CLUSTER SINGLES; HYDROCARBON PHOTOCHEMISTRY; TRICARBON MOLECULES; GAS-CHROMATOGRAPHY; TEMPERATURES; MODEL; STRATOSPHERE; EXPLORATION;
D O I
10.1073/pnas.0900525106
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
For the last four decades, the role of polyynes such as diacetylene (HCCCCH) and triacetylene (HCCCCCCH) in the chemical evolution of the atmosphere of Saturn's moon Titan has been a subject of vigorous research. These polyacetylenes are thought to serve as an UV radiation shield in planetary environments; thus, acting as prebiotic ozone, and are considered as important constituents of the visible haze layers on Titan. However, the underlying chemical processes that initiate the formation and control the growth of polyynes have been the least understood to date. Here, we present a combined experimental, theoretical, and modeling study on the synthesis of the polyyne triacetylene (HCCCCCCH) via the bimolecular gas phase reaction of the ethynyl radical (CCH) with diacetylene (HCCCCH). This elementary reaction is rapid, has no entrance barrier, and yields the triacetylene molecule via indirect scattering dynamics through complex formation in a single collision event. Photochemical models of Titan's atmosphere imply that triacetylene may serve as a building block to synthesize even more complex polyynes such as tetraacetylene (HCCCCCCCCH).
引用
收藏
页码:16078 / 16083
页数:6
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