The scattering vectors are represented by q z and q z,n , and d is the membrane periodicity (Aeffner et al. 2009 ). The phases have been extracted by the 1D swelling method of pure DLPC-lipid samples (Schneggenburger et al. 2009 ). The electron density profile q(z) normal to the interface is computed by N 0 Fourier coefficients f n = I n q z (Eq. 4):