Self-development of cellulose nitrate in linear and nonlinear regimes by ion irradiation

The general shrinkage behaviour of cellulose nitrate is studied as a function of ion fluence in the linear and the nonlinear regimes. During the first one, the self-developed thickness is linearly dependent on the exposure time, and the shrinkage rate follows a linear relationship with the lost energy E1 and the ion influence rate Φ, according to the law v = kE1Φ (k is a constant). In the nonlinear regime, the etch rate seems to be decreasing. We show that this fact is not the result of a change of the nature of the polymer, but that the previous law is still true providing that E1 is the real lost energy in the remaining thickness of cellulose nitrate (CN). No separate effect of the nuclear stopping power Sn or the electronic stopping power Se is observed. (orig.)