The decay rates of three doubly activated phosphors, namely, calcium halophosphate (Mn, Sb), calcium silicate (Mn, Pb), and zinc fluoride (Mn, Ti, or W) have been investigated under λ2537 excitation. The halophosphates studied all show initially a very rapid and abrupt decay, followed by a second stage of decay having a very slow rate. Both stages are of the exponential type. Investigation shows that the rapid rate (decay constant ≈ 1500 sec.−1) is to be ascribed to the antimony emission and the slow rate (k ≈ 75 sec.−1) to the manganese emission.
Calcium silicate behaves in a similar fashion, the ultraviolet emission due to lead decaying rapidly (k ≈ 480 sec.−1) and the visible more slowly (k ≈ 60 sec.−1). The doubly activated zinc fluorides show similar behavior, though the great spectral width of the tungsten band makes separation of the two emission bands difficult.
The fact that in all these cases, the two activators each retain their characteristic decay rates in the presence of the other indicates that two types of centers exist in each of which the process of luminescence functions independently of the other.
© 1949 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
Richard H. Bube
J. Opt. Soc. Am. 39(8) 681-684 (1949)
Frank J. Studer and Gorton R. Fonda
J. Opt. Soc. Am. 39(8) 655-660 (1949)
J. Opt. Soc. Am. 39(1) 42-49 (1949)