Ghosh Debashree, Golan Amir, Takahashi Lynelle K, Krylov Anna I, Ahmed Musahid
Department of Chemistry, University of Southern California , Los Angeles, California 90089-0482, United States.
Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
J Phys Chem Lett. 2012 Jan 5;3(1):97-101. doi: 10.1021/jz201446r. Epub 2011 Dec 16.
The ionization energy of gas-phase deoxyribose was determined using tunable vacuum ultraviolet synchrotron radiation coupled to an effusive thermal source. Adiabatic and vertical ionization energies of the ground and first four excited states of α-pyranose, the structure that dominates in the gas phase, were calculated using high-level electronic structure methods. An appearance energy of 9.1(±0.05) eV was recorded, which agrees reasonably well with a theoretical value of 8.8 eV for the adiabatic ionization energy. A clear picture of the dissociative photoionization dynamics of deoxyribose emerges from the fragmentation pattern recorded using mass spectrometry and from ab initio molecular dynamics calculations. The experimental threshold 9.4 (±0.05) eV for neutral water elimination upon ionization is captured well in the calculations, and qualitative insights are provided by molecular orbital analysis and molecular dynamics snapshots along the reaction coordinate.
利用与喷射热源耦合的可调谐真空紫外同步辐射确定了气相脱氧核糖的电离能。使用高水平电子结构方法计算了α-吡喃糖（气相中占主导地位的结构）基态和前四个激发态的绝热电离能和垂直电离能。记录到的出现能为9.1(±0.05) eV，这与绝热电离能的理论值8.8 eV相当吻合。从质谱记录的碎片模式和从头算分子动力学计算中，可以清晰地了解脱氧核糖的解离光离子化动力学。计算很好地捕捉到了电离时中性水消除的实验阈值9.4(±0.05) eV，并通过分子轨道分析和沿反应坐标的分子动力学快照提供了定性见解。
