Divalent europium ions shew strong absorption bands in the visible and near ultraviolet spectral ragions. Since Hoffman and Hewes

[1

2]

observed in some fluorides sharp lines corresponding to 4f-4f transitions of Eu

2+

ions

great attention has been paid to the study of its spectral properties

[3-8]

. In contrast

[14

15]

to where only the broad 5d-4f emission band was observed in BaYF

5

:Eu

2+

we report in this paper both the broad band and the narrow lines from Eu

2+

in BaYF

5

. Moreover

their excitation and emission spectra have been investigated at 298K and 77K.Fig. 1a

1b and 1c show the emission spectra as a function of Eu

2+

concentration under 260nm UV excitation at 298K and 77K. The emission spectra consist of a broad band corresponding to the 5d-4f transition and narrow line associated with the

6

P

7

-

8

S

7/2

(4f-4f) transition of the Eu

2+

ion. The intensities of both the transitions depend on the Eu

2+

concentration and temperature. There are two bread bands. 4f

6

5d(e

g

) and 4f

6

5d(t

2g

)in excitation spectra. The activators

Eu

2+

are excited by UV from 4f

7

ground state to 4f

6

5d state then luminesce.The radiationless relaxation cf the higher 5d state (t

2g

) gives rise to the

6

P

j

-

8

S

7/2

narrow line emission.