In case of Cu(111), Au(111) and Ag(111) the kF values have been found to be 0.216 nm -1 , 1.73 and 0.080 nm -1 , respectively. The numbers agree with both STM and photoemission measurements. They also agree with an experimental periodicity of approx 1.8 nm for Au(111) and Cu(111). It is also worth to mention that period of oscillations on Cu is slightly smaller than for Au , and it is even smaller for Ag(111) , in accordance with their respective kF values. Crommie et al. and Fujita et al. have analyzed the FOs of Cu and Au surfaces in the form of the above-mentioned equation LDOS(E, x) ∼ 1 -J0(2kF x), where J0 denotes the zeroth-order Bessel function of the first kind 97 . The above equation presents a simplified form of the equation presented in . Later on, the same equation used by Crommie et al. and Fujita et al. has been used by Ono and co-workers, to fit the data obtained for Si(111) √ 3 × √ 3-Ag surface. The authors have observed FOs in tunneling conductance (dI/dV) images, stemming from single point defects with kF = 0.45 nm -1 ). They have also mentioned that long-distance FOs from step-edges have been observed at up to approx. 50 nm distance, similar to most studies presented in this review.