[en] At the present time the technique of deposit of laser ablation is used to produce different types of thin films. At the moment in the National Institute of Nuclear Research (ININ) it is carried out an investigation on the thermoluminescent response of thin films of CN_x with possible application in dosimetry of electromagnetic radiation. Under this context, the present work is part of this investigation and has as objective to characterize thin films of CN_x by means of Infrared spectrometry and nuclear analytical techniques. The deposits were elaborated by laser ablation under different such experimental conditions as: pressure of Nitrogen in the system (3 x 10^-3 and 7.5 X 10^-2 Torr), Distance target-substrate (3 and 5 cm) and density of incident energy in the target (from 17.5 up to 23.8 J/cm²). Graphite of high purity was used like target and the deposits were made on their substrates of intrinsic silicon (100). By means of infrared spectrometry by Fourier Transform (Ftir) the type of bonds which are in the structure of the films of CN_x were determined. The spectra of this type of samples present in general four characteristic bands related with different types of bonds among the elements C, O, H, N such as: C-C, C-N, C-H, N-H, O-H, C=N, C≡N, among others. It was carried out a semi quantitative study of the samples isolating each band of the total infrared spectra and making a comparison between their intensities and forms. This study allowed to observe that there is a dependence of the structure of the films with regard to the time, since mainly bonds of the type Sp³ between Hydrogen and Carbon (C-H) they presented a remarkable variation in intensity, increasing as it lapsed the time until reaching to a stabilization where the bonds already not varying. This increase probably is due to the absorption of water of the atmosphere, although one has seen in the literature that the incorporation of this compound in this type of samples affects mainly to the bonds of the type O-H. To know the mass thickness of the films, their composition, the concentration of each present element in them and the concentration profile in function of the depth for each element the nuclear analytical technique was used: Forward Detection analysis (Elastic Forward Analysis, EFA), with which was could determine quantitatively the amount of C, O, N, H of the samples. It is necessary to mention that the elements O and H is not introduced in the films in a deliberate way, but rather they are introduced in them due to absorption of water coming from the atmosphere or of the residual gas in the ablation chamber. Likewise it was detected and the silicon presence was measured inside the film, which is attributed to diffusion problems inside the same one. The measurements of EFA were carried out with lithium projectiles and of Carbon to different bombardment energy (4 and 10 MeV respectively). It was found that the use of Carbon like projectile presents certain advantages, for this type of films is not very advisable since it happens a phenomenon of loss of material according as the sample is exposed to the beam of ions C³⁺. On the contrary, the projectile of Li²⁺ although it presents some disadvantages in front of the Carbon it seems not to damage the material in question. (Author)