|Abstract:||NO LIF/PLIF has been used extensively in visualizing complex structures of turbulent, reactive, and compressible flows. However, its quantitative measurement capability has been historically limited by the uncertainty in NO fluorescence quantum yield (FQY). In this work, we present a generic model for the FQY of NO $A^2\Sigma^+$(v’=0) based on state-to-state collisional energy transfer calculation. Two energy transfer pathways were considered in this model, namely the collisional quenching/de-excitation of the $A^2\Sigma^+$(v’=0) system down to $X^2\Pi$(v”), and rotational energy transfer between various J levels (up to $\Delta J$ = 30) within $A^2\Sigma^+$(v’=0). Their respective rate constants were modeled using empirical expressions determined from previous data in the literature. Vibrational energy transfer, on the other hand, was not included in the current model, since its rate constants were several orders of magnitude lower than that of collisional quenching and rotational energy transfer. Both steady-state and time-dependent transient analyses, which correspond to pulsed-laser excitation and CW-excitation, respectively, were performed by solving the master equation of quantum state population. The results were compared with direct spectroscopic measurements of NO FQY conducted in a heated gas cell with various collision partners, which in turn, allowed iterative optimization of the quenching and rotational energy transfer rate model. The current model should be useful in predicting NO FQY over a wide range of temperatures and pressures.