Abstract:Please be advised that this information was generated on 2018-05-09 and may be subject to change.PHYSICAL REVIEW A 87, 043425 (2013) Resonant excitation of trapped molecules in a molecular synchrotron We characterize a synchrotron for polar molecules that consists of forty straight hexapoles arranged in a circle. By modulating either the voltages or the duration of the high-voltage pulses that are applied to the hexapoles, we shake the transverse and longitudinal well. If the frequency of the modulation mat… Show more
“…These frequencies are listed in the second column of table 1. In Zieger et al [40], the characteristic frequencies are derived from measurements in which the amplitude, or the duration, of the HV-pulses that are applied to the hexapoles is modulated. …”
We present a synchrotron for polar molecules consisting of 40 straight hexapoles arranged in a circle with a 50 cm diameter. The mechanical design and alignment procedure as well as the trigger scheme used to switch the voltages applied to the hexapoles is described in detail. The stability of the synchrotron is demonstrated by measurements in which multiple packets are stored for over 13 seconds, during which they have completed over 1000 round trips and traveled a distance of over one mile. Furthermore, we demonstrate the simultaneous trapping of 26 packets; 13 revolving clock-wise and 13 counter clock-wise in the ring that are injected into the ring by two Stark decelerator beamlines. We discuss the opportunities for using the synchrotron as low-energy collider.
“…These frequencies are listed in the second column of table 1. In Zieger et al [40], the characteristic frequencies are derived from measurements in which the amplitude, or the duration, of the HV-pulses that are applied to the hexapoles is modulated. …”
We present a synchrotron for polar molecules consisting of 40 straight hexapoles arranged in a circle with a 50 cm diameter. The mechanical design and alignment procedure as well as the trigger scheme used to switch the voltages applied to the hexapoles is described in detail. The stability of the synchrotron is demonstrated by measurements in which multiple packets are stored for over 13 seconds, during which they have completed over 1000 round trips and traveled a distance of over one mile. Furthermore, we demonstrate the simultaneous trapping of 26 packets; 13 revolving clock-wise and 13 counter clock-wise in the ring that are injected into the ring by two Stark decelerator beamlines. We discuss the opportunities for using the synchrotron as low-energy collider.
“…Figure 4 shows the ammonia signal measured in the synchrotron as a function of time. It demonstrates that a packet of ammonia molecules is still clearly visible even after completing more than 1000 round-trips, corresponding to a trapping time of over 13 s. In this time the molecules have traversed a distance of over a mile [ 35 , 38 , 39 ]. Fig.…”
Section: Molecular Synchrotronmentioning
confidence: 99%
“…From these measurements, in combination with trajectory simulations, it is found that the emittance of the stored ammonia – describing the position and velocity spread of the molecules with respect to the so-called synchronous molecule – is [1 mm ·5 m/s] 2 ·[4 mm ·1 m/s]. More details on the synchrotron, the beamline, and the trajectory-simulations of molecules through the synchrotron can be found in Zieger et al [ 35 , 38 , 39 ]. Fig.…”
We have recently demonstrated a general and sensitive method to study low energy collisions that exploits the unique properties of a molecular synchrotron (Van der Poel et al., Phys Rev Lett 120:033402, 2018). In that work, the total cross section for ND3 + Ar collisions was determined from the rate at which ammonia molecules were lost from the synchrotron due to collisions with argon atoms in supersonic beams. This paper provides further details on the experiment. In particular, we derive the model that was used to extract the relative cross section from the loss rate, and present measurements to characterize the spatial and velocity distributions of the stored ammonia molecules and the supersonic argon beams.
“…Each packet of this train is stored for up to 1.2 s, while at a 10 Hz rate new packets are being injected in front of the train and packets at the back of the train are being detected. More details on the synchrotron and injection beam line can be found in Zieger et al [25][26][27].…”
mentioning
confidence: 99%
“…In the detection zone, a quarter ring downstream from the injection point, molecules are ionized via the B-state using light around 317 nm and pushed towards an ion detector by temporarily switching 2 hexapoles to the appropriate voltages. More details on the synchrotron and injection beamline can be found in Zieger et al [23][24][25].…”
We study collisions between neutral, deuterated ammonia molecules (ND 3 ) stored in a 50 cm diameter synchrotron and argon atoms in copropagating supersonic beams. The advantages of using a synchrotron in collision studies are twofold: (i) By storing ammonia molecules many round-trips, the sensitivity to collisions is greatly enhanced; (ii) the collision partners move in the same direction as the stored molecules, resulting in low collision energies. We tune the collision energy in three different ways: by varying the velocity of the stored ammonia packets, by varying the temperature of the pulsed valve that releases the argon atoms, and by varying the timing between the supersonic argon beam and the stored ammonia packets. These give consistent results. We determine the relative, total, integrated cross section for ND 3 þ Ar collisions in the energy range of 40-140 cm −1 , with a resolution of 5-10 cm −1 and an uncertainty of 7%-15%. Our measurements are in good agreement with theoretical scattering calculations. DOI: 10.1103/PhysRevLett.120.033402 The crossed molecular beam technique, pioneered by Herschbach and Lee, has yielded a detailed understanding of how molecules interact and react [1,2]. Until recently, these crossed molecular beam studies were limited by the velocities of the molecular beams to collision energies above a few hundred cm −1 (1 cm −1 ≃ 1.4 K). Over the past years, however, a number of ingenious methods [3][4][5] have been developed to study collisions in the cold regime. These advances are important for several reasons. First, the temperatures of interstellar clouds are typically between 10 and 100 K; collision data of simple molecules at low temperatures are thus highly relevant for understanding the chemistry in these clouds [6]. Furthermore, quantum effects become important at low temperatures, where few partial waves contribute and the de Broglie wavelength associated with the relative velocity becomes comparable to or larger than the intermolecular distances. Of particular interest are resonances of the collision cross section as a function of the collision energy [7][8][9][10]. The position and shape of these resonances are very sensitive to the exact shape of the PES and thus serve as precise tests of our understanding of intermolecular forces.The ability to control the velocity of molecules using time-varying electric fields has allowed studies of inelastic collisions of OH and NO molecules with rare gas atoms at low collision energies [11][12][13][14]. Using cryogenically cooled beams under a small (and variable) crossing angle, inelastic collisions of O 2 and CO with H 2 and helium at energies between 5 and 30 K have been studied [15]. Even lower temperatures can be obtained by using magnetic or electric guides to merge two molecular beams into a single beam. This technique has been used to study Penning ionization reactions of various atoms and molecules with metastable helium [16][17][18][19] and collisions between ground state hydrogen molecules and hydrogen molecules in ...
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