Optical tweezers for sample fixing in micro?diffraction experiments

In order to manipulate, characterize and measure the micro?diffraction of individual structural elements down to single phospholipid liposomes we have been using optical tweezers (OT) combined with an imaging microscope. We were able to install the OT system at the microfocus beamline ID13 at the ESRF and trap clusters of about 50 multi?lamellar liposomes (< 10 ?m large cluster). Further we have performed a scanning diffraction experiment with a 1 micrometer beam to demonstrate the fixing capabilities and to confirm the size of the liposome cluster by X?ray diffraction.