Single Shot Soft X-ray Contact Microscopy with Laboratory Laser Produced Plasmas

Abstract

The high intensities generated by laser produced plasmas in the water window (23–44A) region of the x-ray spectrum make possible single shot contact x-ray microsocopy of living, hydrated biological samples (Baldwin and Rosser, 1986). The short (typically 1ns) laser pulses result in exposure of the specimen image onto the photoresist prior to structural alteration of the specimen by x-ray induced damage. This is a significant advantage over continuous x-ray sources such as synchrotrons, but is a common feature with other flash x-ray sources such as the gas puff z-pinch. However, the laser-plasma x-ray source offers a number of futher advantages: 1. It produces reproducible x-ray intensities with every laser shot. 2. The laser source position is reproducible to within the focussed laser spot size. 3. The small spot size at the laser focus (<100µm) reduces the effect of penumbral shadowing from a source of finite size. 4. The compact geometry of the laser-plasma source allows small (<10mm) source to specimen distances to enhance the x-ray intensity.