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FEMTOSECOND laser pulses that are focused into a gaseous medium can be a source of THz pulse radiation of high intensity and spectral width. Recently in [1], it is suggested using liquid as a source of THz radiation and to use an optical breakdown in water to generate THz waves. Differ-ences between gas and liquid allow us to assume that the mechanisms of the THz radiation should be different as well. First of all, after ionization, in comparison with gas, free electrons in liquids exhib-it a very small free path length, and thus the contri-bution of the free electrons current surge decreases. On the other hand, the nonlinear contribution to the THz signal in liquids should be much bigger than in gases, because the nonlinear susceptibility is six or-ders higher than in the visible range. In this work we study THz generation from a photo induced plasma in nitrogen in gas, liquid (LN) and supercritical fluid. We chose LN instead of wa-ter because, besides exhibiting third-order nonline-arity, this non-polar liquid shows weak-up-to-moderate absorption in the visible and THz frequen-cy ranges, nevertheless this attenuation seems to shift the THz spectrum generated in LN to the low-frequency range.