20 research outputs found
Continuous Centrifuge Decelerator for Polar Molecules
Producing large samples of slow molecules from thermal-velocity ensembles is
a formidable challenge. Here we employ a centrifugal force to produce a
continuous molecular beam with a high flux at near-zero velocities. We
demonstrate deceleration of three electrically guided molecular species,
CHF, CFH, and CFCCH, with input velocities of up to
to obtain beams with velocities below
and intensities of several .
The centrifuge decelerator is easy to operate and can, in principle, slow down
any guidable particle. It has the potential to become a standard technique for
continuous deceleration of molecules.Comment: 5 pages, 4 figures; version accepted for publication in PR
Velocity-selected molecular pulses produced by an electric guide
Electrostatic velocity filtering is a technique for the production of
continuous guided beams of slow polar molecules from a thermal gas. We extended
this technique to produce pulses of slow molecules with a narrow velocity
distribution around a tunable velocity. The pulses are generated by
sequentially switching the voltages on adjacent segments of an electric
quadrupole guide synchronously with the molecules propagating at the desired
velocity. This technique is demonstrated for deuterated ammonia (ND),
delivering pulses with a velocity in the range of and a
relative velocity spread of at FWHM. At velocities around
, the pulses contain up to molecules each. The data are
well reproduced by Monte-Carlo simulations, which provide useful insight into
the mechanisms of velocity selection.Comment: 8 pages, 6 figure
Directional coupling and branching of optical signals by dark beams
ABSTRACT Various types of dark optical beams with respect to their phase dislocation are discussed and their propagation dynamics is analyzed. On the basis of numerical results 1D and 2D optical couplers are proposed. The respective energy efficiencies for each of the output channels are estimated. Multiple charged optical vortices and their topological instability are presented. Through a proper type of perturbation applied to these vortices they could be split into several sub-beams, thus giving the opportunity of proposing all-optical branching schemes. Two output channel distribution schemes for such an optical brancher are discussed
Die Auswirkungen der hohen Unterbeschaeftigung in Ostdeutschland auf die personelle Einkommensverteilung
SIGLEUuStB Koeln(38)-931102091 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Competition between π and σ hydrogen bonds and conformational probing of 2-orthofluorophenylethanol by low- and high-resolution electronic spectroscopy
The flexible model molecule 2-orthofluorophenylethanol has been investigated by laser-induced fluorescence, and low- and high-resolution resonance-enhanced two-photon ionization spectroscopy in combination with high-level ab initio quantum chemistry calculations. One dominant conformation has been identified in the cold molecular beam corresponding to the most stable theoretically predicted gauchestructure stabilized by an intramolecular OH⋯π hydrogen bond. A tentative assignment of a higher-lying gauche conformer present in the molecular beam separated by high potential barriers from the most stable one has been made. The missing other higher-energy theoretically predicted conformations most likely relax to the most stable ones during the process of the adiabatic expansion. The good agreement between the experimental and theoretical results demonstrates that even in the case of a substitution with an electronegative atom at the ortho position, bringing about a significant redistribution of the electron density in the benzene ring and providing a convenient binding site for the formation of a competing OH⋯F σhydrogen bond, the nonclassical OH⋯π bond remains the preferred binding motif for the most stable conformer