We have made a stringent test of time-reversal symmetry using nuclear-spin resonance in a rotationally cold, supersonic beam of thallium fluoride molecules. We searched for a shift of the 120-kHz thallium spin resonance when a 29.5 kV/cm external electric field was reversed relative to the nuclear spin and found this to be (1.4±2.4)×${10}^{\mathrm{-}4}$ Hz. This is a tenfold improvement over our previous measurement in thallium fluoride. The derived constraints on the proton and electron electric dipole moments and on T violation in both strong and weak interactions are correspondingly improved.

• Received 21 August 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.2559