Pulsed operation of a ring Stark decelerator

Abstract

Stark deceleration is a technique that uses time-varying inhomogeneous electric fields to decelerate polar molecules for various molecular beam and trapping experiments. New ring-geometry Stark decelerators with continuously varying voltages offer a method to produce a more intense source of molecules in a technique called traveling-wave Stark deceleration. However, this type of deceleration is more experimentally challenging than the more typically used crossed-pin geometry decelerators with pulsed voltages. Here, we present an experimental realization of a ring-geometry Stark decelerator using either continuously varying or discrete voltages. Pulsed-ring Stark deceleration using discrete voltages is easier to implement and, under certain circumstances, is more efficient than traveling-wave Stark deceleration. A comparison of experimental and simulated results between traveling-wave and pulsed-ring Stark deceleration is presented along with a simple model for determining when each mode is more efficient.

Reactions of Acetonitrile with Trapped, Translationally Cold Acetylene Cations

“…This vacuum ultraviolet light source would also enable detection of contaminants in reactant samples through photoionization experiments. We have also coupled the current apparatus to a traveling-wave Stark decelerator. − This will extend the limits of cold, controlled reaction experiments by enabling control over the neutral reactant, both its quantum state and its velocity, leading to collision energies from 1 to 300 K . Having such reaction energy resolution and quantum control over both reactants will push the limits of our knowledge of fundamental chemical reactions and may provide new insights into astrochemical reactions.…”

Isotope-specific reactions of acetonitrile (CH3CN) with trapped, translationally cold CCl+

“…For the LIT-TOFMS apparatus, future directions also include the integration of a traveling wave Stark decelerator 61,62 to expand control over the internal and external energies of polar neutral molecules. The ability to slow molecules down into the millikelvin regime allows the elucidation of whether quantum mechanical effects to play a greater role ion-neutral chemical dynamics.…”

Quantum-state-specific reaction rate measurements for the photo-induced reaction Ca+ + O2 → CaO+ + O

“…In future work, we plan to extend these types of measurements to more complex systems, such as reactions with organic molecules, and with additional control over the neutral reactant using a Stark decelerator. We will attach a traveling-wave Stark decelerator [40,41] to the ion trap apparatus, similar to the experiments of the Oxford group [42] and the recent proposal by the Willitsch group [43]. This will allow us to tune the velocity of the neutral reactant down to 10 ms −1 , enabling studies of ionmolecule reactions below 10 K. A Stark decelerator can also produce molecules in a single quantum state, thus enabling studies of the influence of the internal molecular states on the reaction.…”