- Published on 17 August 2015
As part of the new Thematic Series ”Methods for Cold Molecules and Ions: Tutorial Reviews” (Guest Eds. Stefan Willitsch, Hendrick Bethlem, Bob Continetti), EPJ Techniques and Instrumentation features two tutorial style articles from the group of Sebastiaan van de Meerakker (Radboud University, Netherlands).
Optimal beam sources for Stark decelerators in collision experiments (EPJ Techniques and Instrumentation 2015, 2:12, DOI 10.1140/epjti/s40485-015-0021-y) by Sjoerd N Vogels, Zhi Gao and Sebastiaan YT van de Meerakker describes the use of the Stark deceleration technique to produce packets of molecules with a tunable velocity, a narrow velocity spread, and a high state purity, for us in high resolution spectroscopy, cold molecule trapping, and controlled scattering experiments. The quality and purity of the packets of molecules emerging from the decelerator critically depend on the specifications of the decelerator, but also on the characteristics of the molecular beam pulse with which the decelerator is loaded. The authors consider three frequently used molecular beam sources, and discuss their suitability for molecular beam deceleration experiments, in particular with the application in crossed beam scattering in mind.
In Analysis of velocity-mapped ion images from high-resolution crossed-beam scattering experiments (EPJ Techniques and Instrumentation 2015, 2:11, DOI 10.1140/epjti/s40485-015-0020-z) by Alexander von Zastrow, Jolijn Onvlee, David H. Parker and Sebastiaan Y.T. van de Meerakker the authors describe how the use of velocity map imaging with the Stark decelerator allows the measurement of scattering images with unprecedented radial sharpness and angular resolution. However, differential cross sections must be extracted from these high-resolution images with extreme care, and common image analysis techniques that are used in crossed beam experiments can result in systematic errors. Using a high-resolution data set on inelastic collisions of velocity-controlled NO radicals with Ne atoms, the authors describe the challenges met by the high resolution, and present methods to mitigate or overcome them.