We have systematically studied the interaction between Mn

2+

and Sm

3+

centers in ZnS. The time resolved luminescence spectra of ZnS:Mn

2+

ZnS:Sm

3+

and znS:Mn

2+

Sm

3+

have been measured.It is found that energy transfer takes place between Mn

2+

ions and Sm

3+

ions.The time resolved luminescence spectra show distinctly the process of the energy transfer from Mn

2+

to Sm

3+

. In case the znS:Mn

2+

Sm

3+

is excited by the light pulse of a dye laser line of 530nm

as shown in Fig.9

the emission of Sm

3+

can be observed only after a delay time larger than 10us. Then

the emission of Sm

3+

increases with the increase of the delay time

followed by a decrease of the Mn

2+

emission band. The Sm

3+

emission reaches its maximum value at about 370us.On the other hand

if ZnS:Mn

2+

Sm

3+

is excited by the light pulse of a N2 laser line of 337nm with which both Mn

2+

and Sm

3+

could be excited

as shown in Fig.6

after excitation the emission of Sm

3+

appears immediately as that of Mn

2+

but the intensity of Sm

3+

emission increases with time until it reaches its maximum value at about 12ns.