We present and characterize a versatile device for studying the controlled interaction of free nanoparticles with supersaturated vapors. It utilizes an rf-ion trap for storing a cloud (>10 8 particles) of singly charged nanoparticles in the sub 10-nm size regime and combines it with a static supersaturation chamber operating at low pressure in free molecular flow regime. This allows for the stable production of a homogeneous zone of variable saturation that can reach very high levels of supersaturation (S > 10 4 ). Compared with diffusion chambers, much higher saturations and more homogeneous saturation fields can be achieved, and convective flow is not an issue. The analysis of adsorption and nucleation processes on the surface of nanoparticles can be performed by mass spectrometry and optical spectroscopy. We discuss the general function principle of the device and demonstrate that it is well suited for studying water adsorption and deposition ice nucleation on metal oxide nanoparticles under the conditions of the upper atmosphere of the Earth and Mars.
A multi-reflection time-of-flight mass separator (MR-ToF-MS) for the enhancement of the performance of the Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN has been built and investigated at an off-line test facility. The MR-ToF-MS consists of two ion-optical mirrors between which oscillating ions are separated according to their different mass-over-charge ratios m/q. Flight paths of several hundreds of meters are folded to an apparatus length of less than one meter. Preliminary tests resulted in a mass-resolving power of up to m/ m ≈ 80,000, and the separation was demonstrated for the isobaric ions CO + and N + 2 . The MR-ToF-MS will support the existing purification methods of ISOLTRAP and will extend the access to nuclides produced with high isobaric contamination yields at the ISOLDE facility.
A novel instrument is presented, which permits studies on singly charged free nanoparticles in the diameter range from 1 to 30 nm using synchrotron radiation in the soft x-ray regime. It consists of a high pressure nanoparticle source, a high efficiency nanoparticle beam inlet, and an electron time-of-flight spectrometer suitable for probing surface and bulk properties of free, levitated nanoparticles. We show results from x-ray photoelectron spectroscopy study near the Si L(3,2)-edge on 8.2 nm SiO(2) particles prepared in a nanoparticle beam. The possible use of this apparatus regarding chemical reactions on the surface of nanometer-sized particles is highlighted. This approach has the potential to be exploited for process studies on heterogeneous atmospheric chemistry.
The lifetimes of three isotopologs of the molecular hydrogen anion have been measured using an electrostatic ion-beam trap. Much longer lifetimes ͑up to ϳ2 ms for D 2 − ͒ than predicted by the most recent calculation are found, and it is proposed that more than one electronic state contributes to the overall lifetimes of these species.
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