HEAT OF FORMATION OF THE CN RADICAL

Three methods were used to determine DELTA-H(f)-degrees(CN): the onset of a continuum in the absorption spectrum of C2N2, determination of the lowest lying A(1)SIGMA(u)- vibrational level of C2N2 whose excitation is followed by detection of CN product, and the cutoff of the nascent CN rotational distribution when a slightly higher vibrational level is excited. The average result of the three determinations is DELTA-H(f)-degrees(CN) = 435.4 +/- 2.0 kJ/mol.