A method and a system for producing a change in a medium. The method places in a vicinity of the medium an energy modulation agent. The method applies an initiation energy to the medium. The initiation energy interacts with the energy modulation agent to directly or indirectly produce the change in the medium. The energy modulation agent has a normal predominant emission of radiation in a first wavelength range outside of a second wavelength range (WR2) known to produce the change, but under exposure to the applied initiation energy produces the change. The system includes an initiation energy source configured to apply an initiation energy to the medium to activate the energy modulation agent.