Slow Decay Processes of Electrostatically Trapped Rydberg NO Molecules

Abstract

Nitric oxide (NO) molecules initially traveling at 795 m=s in pulsed supersonic beams have been photoexcited to long-lived hydrogenic Rydberg-Stark states, decelerated and electrostatically trapped in a cryogenically cooled, chip-based transmission-line Rydberg-Stark decelerator. The decelerated and trapped molecules were detected in situ by pulsed electric field ionization. The operation of the decelerator was validated by comparison of the experimental data with the results of numerical calculations of particle trajectories. Studies of the decay of the trapped molecules on timescales up to 1 ms provide new insights into the lifetimes of, and effects of blackbody radiation on, Rydberg states of NO.

Quantum-state-dependent decay rates of electrostatically trapped Rydberg NO molecules

“…7 arise because of their close proximity to, and mixing with, the n(2) hydrogenic Stark states. 39,47 Spectral features that arise from mixing of the np(0) states and hy- drogenic Stark states are also observed. Despite the np(0) states being shorter lived that the nf(2) states, 40,41 the hydrogenic states populated in both cases are long lived.…”

“…There are two main components to the decay dynamics observed in these data: (i) at early trapping times a fast reduction in signal is observed, reflecting the decay of the Rydberg states predominantly populated upon photoexcitation, and (ii) at later times this reduction slows down reflecting the presence of some molecules in states with longer lifetimes that remain in the trap at late times. 47,74 The data indicated by the open squares in Fig. 5 represent measurements made upon laser photoexcitation in nominally zero electric field, V Mod = 0 V. However, because the mechanism by which long-lived Rydberg-Stark states are populated close to the time of laser photoexcitation depends on M N -mixing that occurs in time-varying electric fields, this can be enhanced by applying a rapidly-varying field in the excitation region when the laser radiation is present.…”

“…This behaviour is a consequence of the motion of the molecules in the trap after it is brought to rest. 32,47 During deceleration the molecules are predominantly located ahead of the electric field minima of the travelling traps. 30 After a trap is stopped the molecules oscillate with a period of ∼ 50µs, as they evolve to fill it.…”

“…The value of F z was taken to be equal to the time-averaged field experienced by the molecules in the electrostatic trap obtained from numerical particle trajectory calculations. 47 For V 0 = 149 V this field was F z = 95 Vcm −1 , and was Physical Chemistry Chemical Physics This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. The decay time constants, τ calc , where first calculated without including effects of vibrational channel interactions (i.e., a (N + ) = 0 in Eq.…”

Deceleration and Trapping of SrF Molecules

“…Magnetic [20,21] and optical [22] analogs of the decelerator have also been developed. Beams of H 2 and NO molecules in Rydberg states have been decelerated and trapped using a Rydberg Stark decelerator [23,24]. Until now, CH 3 F [16] and O 2 [25] are the heaviest molecules to have been trapped following Stark and Zeeman deceleration, respectively.…”