April 20, 1960 [CONTRIBUTION FROM
F"OTODECOMPOSITI0N THE
OF
DIAZOMETHANE
1859
GATESAND CRELLINLABORATORIES OF CHEMISTRY, CALIFORNIA INSTITUTE OF TECHNOLOGY (NO. 2520) AND JOHNS HOPKINS UNIVERSITY]
The Production and Subsequent Photolysis of Transient Products from the Photodecomposition of Diazomethane at 4.2 oK.1,2 BY G. WILSEROBINSON AND MACLYN MCCARTY, JR. RECEIVED SEPTEMBER 3, 1959 The three isotopic modifications of diazomethane, C H Z N ~CHDN2 , and CDzN2have been photolyzed during deposition in solid krypton a t 4.2'K. If light of wave length longer than 3400 A. is used, sharp absorption features appear in the vicinity of 3000 A. from photolyzed CH2Nz and CHDN2, and i t is suggested that these are due to methylene. If this identification is correct the probability is high t h a t the triplet state is the ground state of methylene. Because of the presence of other extremely low-lying excited electronic states in the molecule, the result need not be inconsistent with chemical evidence. Higher energy radiation was found t o bleach the sharp features with the simultaneous appearance of well-known CH or C D spectra and a feature a t 4240 A. tentatively identified as belonging to CNz or HCNz. I n the case of photolyzed CD2N2,there appears to be a n altogether different photochemical mechanism taking place in the solid since nothing equivalent to the above sharp structure could be observed. Instead, a series of reasonably sharp 40 cm.-' doublets, which can also be bleac!ed, appears. I n the photolysis of all these molecules there are further broad absorption features in the region X
