Photolysis of diazomethane in solid matrices at 6 or 10 °K and its subsequent thermoluminescence have been reinvestigated. At 11-12 °K, the thermoluminescence consists of a broad emission at 5220±4 Å and a weak progression with spacing 338 cm-1 in the 6000-7600 Å region, the latter probably due to an impurity. Above 15 °K, the spectrum is dominated by a broad emission (180 cm-1 FWHM) centered at 5987 Å, the red glow detected earlier. The emitter responsible for the 5220 Å feature is not clear, though the frequency is close to that of the atomic K(2D→4S) transition. The 5987 Å emission is best assigned to the C2H4(Z or V→T) transition excited through the reaction of CH2(3B1) molecules either with CH2 or CH2NN. This C 2H4 transition has not previously been accessible to experiment. The infrared spectra of the photolysis products at 10 °K indicate that absorptions at 1115 cm-1 (Ar) and 1109 cm-1 (Xe) can be attributed to ν2, the bending mode of CH2 in its ground state. This assignment may be of significance in the interpretation of photoelectron detachment measurements of the CH2 triplet-singlet splitting, tending to favor the 9 kcal/mole value.