EPR of CH2: A substantially bent and partially rotating ground state triplet

EPR spcetra assignable to ground state triple : CH2 have been observed on photolysis of diazomethane and diazirene at 4 degrees K. Two different systems ascribable to to different crystalline sites are observed with each precursor. Analysis of the spectra shows that the long axis of the molecule is largely fixed while rotation about that is almost free. The most probable value of the HCH angle its 136 degrees, in good agreement with most theoretical calculations and smaller than some values compatible with the electronic spectrum.