The temporally quantized theory constructed recently to account for pr
esumed strictly-irreversible evolution of dynamically isolated and loc
alized nonrelativistic quantum systems is used to describe the process
es of emission, absorption and fluorescence of radiation when such sys
tems interact with otherwise isolated quantized radiation-fields, A Qu
asi-Two-State N-Level Radiative Model of systems, introduced in order
to do so in precise nonperturbative terms, reveals the existence of Sp
ectroscopically Equivalent Transitions. For these, initial transition-
probability-rates and initial decay-rates derived for the processes de
pend identically on the frequency of the radiation involved. They diff
er from that derived for the initial damping-rates of their ensuing os
cillatory behavior. The temporally asymptotic transition-probabilities
derived for them differ even more. For intermediate lapses of time, t
he modulation frequencies of the radiation emitted and/or absorbed and
the decay-rate constants associated with their damping satisfy a univ
ersal inverse-proportionality between them. The possible use of these
expressions to test the theory is described.