Ion/molecule reactions,mass spectrometry and optical spectroscopy in a linear ion trap |
| |
| Institution: | 1. Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching bei München, Germany;2. Department of Physics, Texas A&M University, College Station, TX 77483, USA;1. Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-2805, USA;2. Washington State University, PO Box 644630, Pullman, WA 99164-4630, USA;3. Pacific Northwest National Laboratory, PO Box 999, MSIN J4-80, 902 Battelle Blvd., Richland, WA 99352, USA;1. CERN, Geneva, Switzerland;2. Department of Physics, University of Gothenburg, Gothenburg, Sweden;3. Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany;1. Department of Chemistry, Capital Normal University, Beijing 100048, PR China;2. School of Science, Minzu University of China, Beijing 100081, PR China;3. The College of Materials Science and Engineering, Beijing University of Technology, Beijing 100022, PR China;4. Daxing High School Attached to CNU, Beijing 102600, PR China |
| |
| Abstract: | A linear-geometry, radio-frequency, quadrupole ion trap has been developed to generate, purify, accumulate and study atomic and molecular ions in the gas phase. By employing a trap-based system, both reactant and product ions can be stored for significant time periods, which can both enhance the efficiency of gas-phase reaction processes and create an environment to observe collision products after vibrational and rotational excitations have had time to relax. Relaxation occurs via viscous cooling with a dilute buffer gas or via laser cooling. Furthermore, the setup is particularly useful for performing optical spectroscopy on the trapped ions.Atomic and molecular ovens are used to generate thermal beams of neutral species, which are then ionized by electron bombardment. The ions can be trapped, or they can be collided with neutral molecules (e.g. C60) under well defined experimental conditions. The collision energies are variable over a range from nearly 0 to 200 eV. This feature makes possible studies of complex formation, charge transfer and collision-induced fragmentation as a function of kinetic energy. A wide range of masses of up to 4000 u can be stored and manipulated with this apparatus.Two mass spectrometric techniques for the analysis of trapped ionic species are presented. In one method, parametric excitation of the secular motion is used to generate mass spectra with resolutions as high as 1 part in 800 with a simple experimental setup. The second method is capable of quickly generating mass spectra over the entire range of trapped masses, but has only moderate resolution. These spectra are generated by linearly sweeping the rf-trapping voltage to zero and detecting ions as their trap depth falls below a threshold value. In the trapping volume, which is 10 cm in length and 200 μm in diameter, 106 ions can be loaded and stored, corresponding to an ion density above 108 cm−3. Such densities facilitate spectroscopy of the stored ions. Both laser-induced fluorescence and photodissociation measurements have been carried out with a cw laser system providing near-infrared, visible, and ultraviolet beams. Absolute, total cross-sections and branching ratios of the photodissociation of MgC+60 have been measured. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
