EN
The samples of thin film (d ≈ 40 nm) tetrahedral amorphous carbon (ta-C), deposited by the filtered cathodic vacuum arc have been implanted with N⁺ at a fluence of 3×10¹⁴ cm¯² and ion energy E=20 keV. The induced structural modification of the implanted material results in a considerable change of its optical properties, best manifested by a significant shift of the optical absorption edge to lower photon energies as obtained from optical transmission measurements. This shift is accompanied by a considerable increase of the absorption coefficient (photodarkening effect) in the measured wavelength range (350÷2500 nm). These effects could be attributed to both the additional defect introduction and the increased graphitization, as confirmed by the X-ray photoelectron spectroscopy measurements. The optical contrast thus obtained (between implanted and unimplanted film materials) could be made use of in the area of high-density optical data storage using the focused ion beams.