The Eu

2+

halophosphates are studied in the time-resolved station(U10B) of the National Synchrotron Radiation Lab. The (Ca

Sr

Ba)

5

(PO

4

)

3

Cl:Eu

2+

and (Ca

Sr

Ba)

5

(PO

4

)

3

Cl:Eu

2+

samples are studied on the irradiation properties and the reflection spectra. Excited by the 185nm

the decrease of the emission intensity of (Ca

Sr

Ba)

5

(PO

4

)

3

Cl:Eu

2+

is not observed in 60 minutes; on the other hand

the emission intensity of (Ca

Sr

Ba)

5

(PO

4

)

3

Cl:Eu

2+

is observed to have a stronger decrease in 15 minutes. According to the reflection spectra of the two samples(from 100nm to 400nm)

there is a large difference on 185nm between two samples. At the same time

in the absorption spectra got by the K-K relation

the absorption efficiency of two samples are different. We think:when the Ba

2+

is added into the sample

the crystal symmetry is changed

then the (O)

-

energy level changed. The 185nm excitation efficiency of the electron from (O)

-

center decreased. So it can resist the 185nm radiation.