Characterization of extreme ultraviolet light-emitting plasmas from a laser-excited fluorine containing liquid polymer jet target

Abstract

The operation of a liquid polymer jet laser-plasma target and the characterization of the absolute x-ray emission in the extreme ultraviolet wavelength window from 9–19 nm is reported. The target is a liquid polymer (perfluoro-polyether) that is exposed to pulsed and focused laser light at 532 nm in the form of a thin, liquid microjet (d=40 to 160 μm) in vacuum. The spectral brightness of the source in the 13 nm range is relatively high because a large fraction of radiative energy is emitted in one single line only, which is assigned to be the 2p–3d FVII doublet at 12.8 nm, with a laser energy conversion efficiency of 0.45% (2π sr, 2% bandwidth) in our initial experiment. A further increase of the relative emission has been found in the wavelength range between 7 and 17 nm when the jet diameter was increased from 40 to 160 μm. The two-dimensional spatial profile of the source plasma (d=40 to 50 μm) has been analyzed with a pinhole camera.

XUV laser-plasma source based on solid Ar filament

“…Thus, it is possible to study biological samples of several microns thickness in their aqueous environment with a spatial resolution on the nanometer scale ͓15 nm 4 ͔. For the generation of soft x-rays with laser produced plasmas different targets have been investigated, including gas puffs, 5-7 clusters, 8 liquids, [9][10][11][12] and solids. [13][14][15][16] Depending on the target materials broad band as well as narrow band emissions can be obtained that can be matched to specific applications such as x-ray microscopy, 17 reflectometry, 18 near-edge x-ray absorption fine structure ͑NEXAFS͒, 19 etc.…”