ΔHf: 4.6 kcal/mol, REF: D. R. Stull, H. Prophet, Natl. Stand., Ref. Data Ser. (U.S., Natl. Bur. Stand.) NSRDS-NBS 37, 1971. I.P.: 10.1 eV, REF: K. H. Hellwege, A. M. Hellwege, Eds. "Molecular Constants from Microwave Spectroscopy," Landolt-Bornstein, New Series II; Springer-Verlag; Berlin, Vol. 4, (1967).