Stopping molecular rotation using coherent ultra-low-energy magnetic manipulations
Helen Chadwick, Mark F. Somers, Aisling C. Stewart, Yosef Alkoby, Thomas J. D. Carter, D. Butkovičová, Gil Alexandrowicz
Abstract
Abstract Rotational motion lies at the heart of intermolecular, molecule-surface chemistry and cold molecule science, motivating the development of methods to excite and de-excite rotations. Existing schemes involve perturbing the molecules with photons or electrons which supply or remove energy comparable to the rotational level spacing. Here, we study the possibility of de-exciting the molecular rotation of a D 2 molecule, from J = 2 to the non-rotating J = 0 state, without using an energy-matched perturbation. We show that passing the beam through a 1 m long magnetic field, which splits the rotational projection states by only 10 −12 eV, can change the probability that a molecule-surface collision will stop a molecule from rotating and lose rotational energy which is 9 orders larger than that of the magnetic manipulation. Calculations confirm that different rotational orientations have different de-excitation probabilities but underestimate rotational flips (∆ m J $$\ne$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>≠</mml:mo> </mml:math> 0), highlighting the importance of the results as a sensitive benchmark for further developing theoretical models of molecule-surface interactions.