The existence of gaseous CoF4-a species with an unusually high degree of ox
idation of the metal-has been demonstrated by means of Knudsen effusion mas
s spectrometry and FTIR spectroscopy. The Knudsen effusion mass spectrometr
y method has been applied to investigate the gas-phase composition over the
CoF3(s)-TbF4(s) system and to establish the optimum in situ conditions for
CoF4 synthesis. The electron impact mass spectrum of the CoF4 molecule has
been obtained. From the infrared spectrum of argon-isolated CoF4 molecules
, the Co-F stretching mode has been detected at 767.8 cm(-1).