Photoelectron-photofragment coincidence spectroscopy in a cryogenically cooled linear electrostatic ion beam trap
Photoelectron-photofragment coincidence spectroscopy in a cryogenically cooled linear electrostatic ion beam trap
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DOI：
10.1063/1.3641875
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发表时间：
2011-10-01
影响因子：
1.6
通讯作者：
Continetti, Robert E.
中科院分区：
文献类型：
--
作者：
Johnson, Christopher J.;Shen, Ben B.;Continetti, Robert E.
本文描述了一种用于光电子-光碎片符合谱（PPC）的低温冷却线型静电离子束阱。使用这种仪器，在冷，低占空比源中产生的阴离子可以在类似于20 K的环境中存储数秒，以辐射冷却，消除由于振动激发的前体阴离子而产生的能量不确定性。该装置保持高分辨率碎片成像所需的良好准直光束和符合实验所需的高实验占空比。离子振荡被聚束并锁相到锁模激光器，确保离子聚束和激光脉冲之间的时间重叠，并且离子仅在沿一个方向行进时被激光器阻挡。一个电子探测器被安置在陷阱的无场中心，允许PPC实验进行离子，而他们被存储和允许有效的检测三维电子和中性反冲轨迹。为了优化中性粒子分辨率，研究了激光离子相互作用区域中俘获参数对质心运动轨迹的影响，并建立了聚束效应对离子振荡的影响。最后，初步演示辐射冷却。(C)2011年美国物理学会。[doi：10.1063/1.3641875]
A cryogenically cooled linear electrostatic ion beam trap for use in photoelectron-photofragment coincidence (PPC) spectroscopy is described. Using this instrument, anions created in cold, low-duty-cycle sources can be stored for many seconds in a similar to 20 K environment to cool radiatively, removing energetic uncertainties due to vibrationally excited precursor anions. This apparatus maintains a well-collimated beam necessary for high-resolution fragment imaging and the high experimental duty cycle needed for coincidence experiments. Ion oscillation is bunched and phase-locked to a modelocked laser, ensuring temporal overlap between ion bunches and laser pulses and that ions are intersected by the laser only when travelling in one direction. An electron detector is housed in the field-free center of the trap, allowing PPC experiments to be carried out on ions while they are stored and permitting efficient detection of 3-dimensional electron and neutral recoil trajectories. The effects of trapping parameters on the center-of-mass trajectories in the laser-ion interaction region are explored to optimize neutral particle resolution, and the impact of bunching on ion oscillation is established. Finally, an initial demonstration of radiative cooling is presented. (C) 2011 American Institute of Physics. [doi:10.1063/1.3641875]