glowing effect in blender

Hi all,
i am trying to simulate a situation in which there is a sphere in the scene.The sphere is covered with material which is sensitive to infra red light.When infra red light falls on this sphere it shines.This shining effect is more in the center of sphere but it decays towards the edge of sphere where it becomes black.In my case the normal lamp is supposed to be the infra red light source.When sphere is inside the cone of lamp it must show the above mentioned effect.Also i can’t fix the light on this sphere(track to constraint).
Any idea would be appreciated.