An Einstein is defined as a mole of photons.
 
Therefore: microEinsteins per m² per second is identical to micromoles per m² per second.
      1000 µE m^-2 s^-1 = 1000 µmol m^-2 s^-1

Einsteins were interchangeably used along with µmol m^-2 s^-1 in the 60's and 70's, but the
Einstein is not a unit in the SI (International System) of units so using moles is preferred.

For more information see:
Units, Symbols, and Terminology for Plant Physiology
A Reference for Presentation of Research Results in the Plant Sciences
Edited by Frank B. Salisbury
Oxford University Press, 1996