Unwin James, Razmus Weronika O, Allum Felix, Harries James R, Kumagai Yoshiaki, Nagaya Kiyonobu, Britton Mathew, Brouard Mark, Bucksbaum Philip, Fushitani Mizuho, Gabalski Ian, Gejo Tatsuo, Hockett Paul, Howard Andrew J, Iwayama Hiroshi, Kukk Edwin, Lam Chow-Shing, McManus Joseph, Minns Russell S, Niozu Akinobu, Nishimuro Sekito, Niskanen Johannes, Owada Shigeki, Pickering James D, Rolles Daniel, Somper James, Ueda Kiyoshi, Wada Shin-Ichi, Walmsley Tiffany, Woodhouse Joanne L, Forbes Ruaridh, Burt Michael, Warne Emily M
Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom.
School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
ACS Phys Chem Au. 2024 Aug 10;4(6):620-631. doi: 10.1021/acsphyschemau.4c00036. eCollection 2024 Nov 27.
Time-resolved extreme ultraviolet spectroscopy was used to investigate photodissociation within the iodobenzene C-band. The carbon-iodine bond of iodobenzene was photolyzed at 200 nm, and the ensuing dynamics were probed at 10.3 nm (120 eV) over a 4 ps range. Two product channels were observed and subsequently isolated by using a global fitting method. Their onset times and energetics were assigned to distinct electron transfer dynamics initiated following site-selective ionization of the iodine photoproducts, enabling the electronic states of the phenyl fragments to be identified using a classical over-the-barrier model for electron transfer. In combination with previous theoretical work, this allowed the corresponding neutral photochemistry to be assigned to (1) dissociation via the 7B, 8A, and 8B states to give ground-state phenyl, Ph(X), and spin-orbit excited iodine and (2) dissociation through the 7A and 8B states to give excited-state phenyl, Ph(A), and ground-state iodine. The branching ratio was determined to be 87 ± 4% Ph(X) and 13 ± 4% Ph(A). Similarly, the corresponding amount of energy deposited into the internal phenyl modes in these channels was determined to be 44 ± 10 and 65 ± 21%, respectively, and upper bounds to the channel rise times were found to be 114 ± 6 and 310 ± 60 fs.
利用时间分辨极紫外光谱研究了碘苯C波段内的光解离。碘苯的碳 - 碘键在200 nm处发生光解，随后在10.3 nm（120 eV）处对4 ps时间范围内的后续动力学进行了探测。观察到两个产物通道，并随后通过全局拟合方法将其分离。它们的起始时间和能量学被归因于碘光产物进行位点选择性电离后引发的不同电子转移动力学，从而能够使用经典的电子转移势垒模型来识别苯基片段的电子态。结合先前的理论工作，这使得相应的中性光化学过程能够被确定为：（1）通过7B、8A和8B态解离生成基态苯基Ph(X)以及自旋 - 轨道激发态碘；（2）通过7A和8B态解离生成激发态苯基Ph(A)以及基态碘。确定分支比为87±4%的Ph(X)和13±4%的Ph(A)。同样，在这些通道中沉积到苯基内部模式的相应能量分别确定为44±10%和65±21%，并且发现通道上升时间的上限分别为114±6 fs和310±60 fs。
