Force gradient detection under vacuum on the basis of a double pass method

Abstract

The feasibility of detecting electrostatic gradients in the linear regime is shown under vacuum by combining intermittent contact atomic force microscopy and a double pass method. To achieve our goal, different flexure mode orders were employed. We show that the sensitivity of the frequency or phase shifts to a given gradient was reduced when the order was increased. This behavior is theoretically explained in quantitative agreement with the experiments. Thus, on the basis of different flexure mode orders, gradient detection can now be extended to other forces plus various environments, i.e., under vacuum or controlled atmosphere.