TrapREMI: A reaction microscope inside an electrostatic ion beam trap

Abstract

A new experimental setup has been developed to investigate the reactions of molecular ions and charged clusters with a variety of projectile beams. An Electrostatic Ion Beam Trap (EIBT) stores fast ions at keV energies in an oscillatory motion. By crossing it with a projectile beam, e.g., an IR laser, molecular reactions can be induced. We implemented a Reaction Microscope (REMI) in the field-free region of the EIBT to perform coincidence spectroscopy on the resulting reaction products. In contrast to prior experiments, this unique combination of techniques allows us to measure the 3D momentum-vectors of ions, electrons, and neutrals as reaction products in coincidence. At the same time, the EIBT allows for advanced target preparation techniques, e.g., relaxation of hot molecules during storage times of up to seconds, autoresonance cooling, and recycling of target species, which are difficult to prepare. Otherwise, the TrapREMI setup can be connected to a variety of projectile sources, e.g., atomic gas jets, large-scale radiation facilities, and ultrashort laser pulses, which enable even time-resolved studies. Here, we describe the setup and a first photodissociation experiment on [Formula: see text], which demonstrates the ion-neutral coincidence detection in the TrapREMI.

Open questions on the interaction dynamics of molecules and clusters in the gas phase

“…These allow for studies of, e.g., (i) charge-, mass- and energy- transfer processes in sub-eV collisions between pairs of oppositely charged ions (see, e.g., Grumer et al 10 and references therein), (ii) reactions between stored ions and free electrons or neutrals (atoms or molecules) that may be fine-tuned down to micro- and millielectronvolts 11 , and (iii) studies of ultraslow fragmentation, electron emission and radiative cooling (vibrational and rotational relaxation) processes up to hundreds of seconds 1 , 12 . In recent years there has also been a strong development of compact and versatile ion beam storage devices designed for, e.g., merged beams interactions 13 and for providing kinematically complete information on reactions induced in interactions with a variety of projectile beams 14 .…”

Simultaneous electrostatic trapping of merged cation & anion beams

“…55,56 The EIBT technology has been implemented in a broad range of electrostatic trapping applications. 38,[57][58][59] In particular, taking advantage of the repulsive ion-ion interaction that has been demonstrated to result in surprising counterintuitive ion-bunch dynamics with application to high-resolution mass-spectrometry, 26,60 as well as for ion beam cooling applications. 37,57,61 It will therefore be valuable to extend EIBT based technology to allow merged beam experiments.…”