Spectroscopic version of the Aharonov-Bohm effect
  An experiment is proposed in which the Aharonov-Bohm effect can be veryfied through a spectroscopic measurement. The apparatus consists of gaseous hydrochloric acid (HCl) immersed in the vector potential ${\bf A}$ present in the center of a toroidal coil, where ${\bf B}=0$. Changes due to ${\bf A}$ in the absorption spectrum of the gas are investigated. 
C. Lagan\'a
quant-ph