Bias voltage plays an even more important role in FOs observation, as its decrease allows for a much clearer image in STM. Fujita et al., have noted that for herringbone reconstructed Au(111) surface at a bias voltage of -2mV, they have been able to detect long-range spatial oscillations, unlike in their previous measurements at 30mV. To the best of our knowledge bias voltage below 100mV gives the most well-defined FOs . The reason for such observation is that smaller bias voltage probes closer to the Fermi level, without causing much disturbance to the material.