In this paper

the series of absorption

excitation and emission spectra of REP

5

O

14

(RE = Ce

3+

Pr

3+

Nd

3+

Sm

3+

Eu

3+

Gd

3+

Tb

3+

Dy

3+

Ho

3+

Er

3+

Tm

3+

Yb

3+

) single crystals were investigated in a wavelength region much larger than those reported so far. The spectral terms were assigned reasonably

and some mistakes in previous papers were corrected. Particularly

the spectra for GdP

5

O

14

DyP

5

O

14

TmP

6

O

14

YbP

5

O

14

and SmP

5

O

14

were measured in detail. They have not been reported previously. These spectral data will be very useful to understand the properties of REP

5

O

14

crystals and to utilize them.