To methods have been used to determine the non-radiative transition probability of

5

D

1

state of Eu

3+

.(1)Partlo's method.The quantum efficiency from state A to state B(Fig.4) can be obtained from the absorption spectrum and the excitation spectrum according to formula(1)

where

P

A

and

P

B

are the power absorbed by A and B respectivel

P

AL

and P

BL

are the emission intensities of L generated by excitation to A state and B state respectivel

and

v

A

and

v

B

are respectively the energies(in wavenumber) of A and B. The absorption spectrum of the phosphor can be determined from the diffuse reflection spectrum according to our previous work. The quantum efficienc from

5

D

1

to

5

D

0

is then determined to be 79.6%. The non-radiative transition probability of

5

D

1

is 5.64×10

-3

/sec.(2)Judd-Ofelt's method. In calculating the intensity parameters j(j=2

4

6) from the emission spectrum according to J-O theory the index of refraction n of LaOCl(which is unkno n) is evaluated by the method we proposed in a recent paper.The nonradiative transition probability of

5

D

1

which can be obtained from the radiative transition probability of

5

D

1

to

7

F

j

(for all j values) and the measuied lifetime

is 5.28×10

-3

/sec

which agree fairly well with the fromer value.It appears that the first method is more convenient and probably more accurate.