N2O molecules dispersed in argon matrices, at a concentration of 1/2000, are excited to their v(3) = 1 vibrational level by a laser pulse at 2218 cm(-1). Stimulated emission of the vs-vl transition is observed when the inversion population is large enough, i.e., when the energy absorbed from the laser pulse exceeds a threshold value. From the measured energy threshold, we derive a ＇＇loss coefficient" for the cavity-like, polycrystalline excited argon sample (a disk about 200 mu m thick and 1.5 mm in diameter). Using this loss coefficient, on the basis of molecular spectroscopic parameters, we predict the inversion population threshold for stimulated emission on other N2O transitions, and for other molecules in identical matrices. The prediction is remarkably consistent with our previous observations on O-3 and (CO2)-C-13 for which the emitting level (v(3) = 2 and v(2) = 3 or 2, respectively) is populated via intramolecular nonradiative transfers.