1,721,032 research outputs found
A molecular synchrotron
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76078.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 22 januari 2009Promotor : Meijer, G.J.M. Co-promotor : Bethlem, H.L.146 p
A synchrotron for polar molecules
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100603.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 07 december 2012Promotor : Meijer, G.J.M. Co-promotores : Bethlem, H.L., Meerakker, S.Y.T. van de115 p
AC trapping and high-resolution spectroscopy of ammonia molecules
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29874.pdf (Publisher’s version ) (Open Access)Cold molecules are potentially beneficial for several areas of research. They have applications in spectroscopy, collision studies and, for instance, the study of the effects of dipole-dipole interactions in BECs. One method to decelerate and thereby cool down neutral dipolar molecules is to use a Stark decelerator. In my thesis, I show the advantages of cold, Stark-decelerated molecules in a high-resolution spectroscopy experiment, using the pure inversion motion of ammonia molecules. The transition associated with this motion is measured both on a warm and on a cold beam, resulting in an increased resolution in the latter case. For many of the applications of cold molecules mentioned above, molecules in high-field seeking states are necessary. To induce molecules to form a BEC, ground state molecules, which are always high-field seeking, are necessary for the use of preliminary cooling methods like evaporative cooling, as trap loss due to inelastic collisions is absent in this state. Many of the more interesting spectroscopy experiments, like experiments with biomolecules or experiments involved with the testing of fundamental physics theories, need to be performed on heavy molecules. Most states in these molecules are high-field seeking as well. To be able to better study high-field seeking molecules, it is important that we are able to confine a cold sample of such molecules in a trap. For this, a so-called AC trap is needed. The first electrical AC trap for molecules is demonstrated in this thesis. It utilizes two fields that are shaped like a saddle point. One of the fields is rotated over 90 degrees with respect to the other. By switching between these two fields, a molecule will alternately experience a focusing (maximum in the electric field strength) and defocusing force (minimum in the electric field strength) in each direction. At the appropriate switching frequency, the overall force is focusing and the molecules remain trappedRadboud University, Molecular and Biophysics, Frit, 11 december 2006Promotor : Meijer, G.J.M. Co-promotor : Bethlem, H.L.145 p
Femtosecond laser detection of xenon and Stark decelerated polyatomic molecules
Full text linkUbachs, W.M.G. [Promotor]Bethlem, H.L. [Copromotor
Polyatomic molecules for probing a possible variation of the proton-to-electron mass ratio
Full text linkUbachs, W.M.G. [Promotor]Bethlem, H.L. [Copromotor
Cold Collisions in a Molecular Synchrotron
Full text linkUbachs, W.M.G. [Promotor]Bethlem, H.L. [Copromotor
Molecular radicals in the search for drifting constants
Full text linkUbachs, W.M.G. [Promotor]Bethlem, H.L. [Copromotor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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