School of Nuclear Science and Technology, National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China.
J Chem Phys. 2011 May 7;134(17):174306. doi: 10.1063/1.3575401.
The vacuum-ultraviolet photoionization and dissociative photoionization of 1,3-butadiene in a region ∼8.5-17 eV have been investigated with time-of-flight photoionization mass spectrometry using tunable synchrotron radiation. The adiabatic ionization energy of 1,3-butadiene and appearance energies for its fragment ions, C(4)H(5)(+), C(4)H(4)(+), C(4)H(3)(+), C(3)H(3)(+), C(2)H(4)(+), C(2)H(3)(+), and C(2)H(2)(+), are determined to be 9.09, 11.72, 13.11, 15.20, 11.50, 12.44, 15.15, and 15.14 eV, respectively, by measurements of photoionization efficiency spectra. Ab initio molecular orbital calculations have been performed to investigate the reaction mechanism of dissociative photoionization of 1,3-butadiene. On the basis of experimental and theoretical results, seven dissociative photoionization channels are proposed: C(4)H(5)(+) + H, C(4)H(4)(+) + H(2), C(4)H(3)(+) + H(2) + H, C(3)H(3)(+) + CH(3), C(2)H(4)(+) + C(2)H(2), C(2)H(3)(+) + C(2)H(2) + H, and C(2)H(2)(+) + C(2)H(2) + H(2). Channel C(3)H(3)(+) + CH(3) is found to be the dominant one, followed by C(4)H(5)(+) + H and C(2)H(4)(+) + C(2)H(2). The majority of these channels occur via isomerization prior to dissociation. Transition structures and intermediates for those isomerization processes were also determined.
采用可调谐同步辐射的飞行时间光电离质谱法，研究了 1,3-丁二烯在 8.5-17 eV 区域的真空紫外光电离和离解光电离。通过光电离效率谱的测量，确定了 1,3-丁二烯的绝热电离能和碎片离子 C(4)H(5)(+)、C(4)H(4)(+)、C(4)H(3)(+)、C(3)H(3)(+)、C(2)H(4)(+)、C(2)H(3)(+)和 C(2)H(2)(+)的出现能分别为 9.09、11.72、13.11、15.20、11.50、12.44、15.15 和 15.14 eV。通过从头算分子轨道计算，研究了 1,3-丁二烯离解光电离的反应机制。基于实验和理论结果，提出了七种离解光电离通道：C(4)H(5)(+) + H、C(4)H(4)(+) + H(2)、C(4)H(3)(+) + H(2) + H、C(3)H(3)(+) + CH(3)、C(2)H(4)(+) + C(2)H(2)、C(2)H(3)(+) + C(2)H(2) + H 和 C(2)H(2)(+) + C(2)H(2) + H(2)。发现 C(3)H(3)(+) + CH(3)通道是主要通道，其次是 C(4)H(5)(+) + H 和 C(2)H(4)(+) + C(2)H(2)。这些通道中的大多数都是通过离解前的异构化发生的。还确定了这些异构化过程的过渡态结构和中间体。
