We report mass spectrometric evidence supporting our proposed mechanistic pathway for the production of N4 through the energy pooling reaction N2 A3Sigma(u)+ + N2 A3Sigma(u)+. N2 A3Sigma(u)+ is generated from the quenching of resonantly excited xenon in a mixture of xenon, 15N2, and 14N2 that is illuminated with xenon resonant lamps (147 nm). Mass spectra are periodically taken of the mixture. Over time, we observe significant isotopic scrambling of the 15N2 and 14N2, generating 15N14N in concentrations approaching 10% (approximately 2 Torr) of the initial 15N2 concentration. Though we do not observe the direct formation of N4, the isotopic ratios indicate that an excited complex (15N2(14)N2) exists long enough so that scrambling of the nitrogen atoms can occur, offering a possible route to the formation of tetrahedral nitrogen (1Td N4).