X-ray pushing of a mechanical microswing

Abstract

Nanoelectromechanical Systems (NEMS) are among the best candidates to measure interactions at nanoscale [1,2,3,4,5,6], especially when resonating oscillators are used with high quality factor [7,8]. Despite many efforts [9,10], efficient and easy actuation in NEMS remains an issue [11]. The mechanism that we propose, thermally mediated Center Of Mass (COM) displacements, represents a new actuation scheme for NEMS and MEMS. To demonstrate this scheme efficiency we show how mechanical nanodisplacements of a MEMS is triggered using modulated X-ray microbeams. The MEMS is a microswing constituted by a Ge microcrystal attached to a Si microcantilever. The interaction is mediated by the Ge absorption of the intensity modulated X-ray microbeam impinging on the microcrystal. The small but finite thermal expansion of the Ge microcrystal is large enough to force a nanodisplacement of the Ge microcrystal COM glued on a Si microlever. The inverse mechanism can be envisaged: MEMS can be used to shape X-ray beams. A Si microlever can be a high frequency X-ray beam chopper for time studies in biology and chemistry. Previous studies of light mechanical effects on MEMS and NEMS have shown radiation pressure [12] or thermal switch effect in the lever [13] as actuation mechanism for mechanical systems. We show that these effects are not effective enough to induce the observed oscillation amplitude in our experiments. The experimental set-up is presented in fig.

Dynamical backaction cooling with free electrons

“…4). This asymmetry reflects that of the force exerted by the electron beam and is a signature of thermally-induced bending at the nanoscale [43,44].…”

A MEMS-based high frequency x-ray chopper

“…The interactions between x-ray techniques and MEMS technology have been recently shown in work where a modulated x-ray beam has been used to excite a mechanical system around its first-order resonance [15]. At variance we show here how the inverse mechanism can be used to modulate an x-ray beam.…”

“…The cantilever displacement is measured by the interference between the light reflected from the end of a cleaved optic fiber and the beam reflected by the back of the lever. This interferometric technique has been shown to lead to sub-ångström precision in position measurement [15][16][17][18].…”