The motional electric field experienced by an ${\mathrm{H}}_2^{+}$ ion moving in a magnetic field induces an electric dipole, so that one-photon dipole transitions between rovibrational states become allowed. Field-induced spontaneous decay rates are calculated for a wide range of states. For an ion stored in a high-field ($B\sim 10$ T) Penning trap, it is shown that the lifetimes of excited rovibrational states can be shortened by typically 1–3 orders of magnitude by placing the ion in a large cyclotron orbit. This can greatly facilitate recently proposed [E. G. Myers, Phys. Rev. A 98, 010101 (2018).] high-precision spectroscopic measurements on ${\mathrm{H}}_2^{+}$ and its antimatter counterpart for tests of $CPT$ symmetry.

• Received 9 October 2018

DOI:https://doi.org/10.1103/PhysRevA.98.062501