ULTRAVIOLET STUDY FOR ADSORPTION OF PYRIDINE AND 2,2'-BIPYRIDYL ON EVAPORATED METAL FILMS

Ultraviolet spectra for pyridine adsorbed on Ti, Fe, and Ni, and those for 2,2′-bipyridyl on Ti, Mn, Fe, Ni, and Cu are reported. The adsorbed pyridine on Ti gives a band at 257 mμ, on Fe two bands at 258 and 297 mμ, and on Ni a band with peaks of vibrational structure at 265.5, 260, 254.3, and 248 mμ. These bands near 260 mμ were assigned to π-π* (1Lb) transition of the adsorbed pyridine. The 297-mμ band on Fe was assigned to a charge-transfer band and two types of π interaction were examined between π orbitals of the pyridine ring and dπ orbitale of adsorbent metal atoms. The spectral variations depending on these metals are discussed on the basis of the pyridine-metal bond character. The adsorbed 2,2′-bipyridyl gives two bands near 240 and 285 mμ on the metals used. Spectral change of the adsorbed species by evacuation shows an existence of species on various energy sites. Effects of admission of air on the spectra are also reported.