Modeling of dissolution and resolution in contact x-ray microscopy

Contact x-ray microscopy or microradiography offers a simple-to-use approach to high resolution imaging of wet, thick biological specimens. One great advantage of the technique is that it can be usedwith short pulse, incoherent x-ray sources such as laser produced plasmas, and polymer replicas or direct AFM viewing are promising new approaches to image readout. However, it has long been pointed outthat issues such as diffraction blurring over finite sample-to-resist spacing, shot noise in the exposure, and sidecutting during development must be considered in evaluating contact x-ray microradiographs.We present here the results of numerical modelling of contact x-ray microscopy using photoresists. We assume a phantom consisting of protein rods and balls of different diameters, all embedded in a water layer. We assume that the x-ray exposure is provided by a black body source with temperature kBT = 100 eV (such as in a laser-produced plasma), and that the black bodyspectrum is then modified by x-ray transmission in 0.1/μm of Al2O3, 0.1μm of Si3N4, and 5μm of water.