2 ions the free holes trapped by ce 3 ions are released as the phosphor heats up due to the absorption of optical photons from the far infrared laser the emission peaks when the phosphor has been heated by the far infrared laser to around 180 u00b0 c while there are peaks that occur at lower temperatures these peaks fade over time in contrast the high temperature peaks remain stable for a longer period of time accordingly it is the high temperature thermal luminescence peaks that are of interest the holes that are released recombine with the sm 2 ion which results in sm 3 emission the sm 3 emission peaks in the orange red region around 609 nanometers regardless of the nature of the second dopant fig3 is a graph showing both the optical and thermal stimulated emission of mgs ce sm the mechanism behind the type of luminescence caused by a near and a far infrared laser will now be explained with the use of the phenomenological model shown in fig4 in conjunction with the graph of fig3 in the case of the optically stimulated luminescence emission electrons are stimulated from the sm 3 ion traps which eventually recombine with the holes trapped at the ce 3 ions that act as recombination centers optically stimulated luminescence emission of mgs ce sm is a doublet with peaks at around 527 nanometers and 580 nanometers which can be identified as ce 3 transitions to the 2 f 5.