A. Morozov

Applications of a broadband electron-beam pumped XUV radiation source

A simple table-top windowless system for extreme ultraviolet (XUV) spectroscopy which avoids differential pumping for both the radiation source and the detector is presented. The radiation source uses excimer emission from rare gases excited with low energy (13 keV) electron beam. Broadband emission in the entire wavelength range from 60 to 140 nm is demonstrated using He, Ne and a Ne–Ar gas mixture. It was observed that the so-called third continuum is absent in Ne when low energy electron-beam excitation is used in contrast to earlier results using high energy ion beam excitation. An application of the set-up for a LiF transmission measurement close to the cut-off wavelength (105 nm) is demonstrated. It is shown how the radiation source could be applied in a simple and efficient technique of material treatment with XUV/VUV radiation.

Electron Beam Pumped Ultraviolet Light Sources

Low energy electron beam excitation of dense gases is used for developing UV and VUV light sources. Emission spectra for various gases are shown and a first application for single photoionization in a time of flight mass spectrometer is presented.

Detection of security relevant substances within the cooperative project SAFE XUV

The objective of this project funded by the German BMBF was to show that security relevant substances can be detected in complex matrices at low concentrations using single photon ionization ion trap mass spectrometry (SPI-ITMS). The advantage of such a soft ionization technique is a reduction of unwanted fragment ions in mass spectra allowing identification of signals from complex matrices and enabling MS/MS capability. The MS/MS studies permit low false-positive and false-negative rates. Additionally, the accumulation of the ions in the ion trap decreases the detection limit. To obtain low detection limits the ionization potentials (IPs) of the relevant substances have to be below the IPs of the bulk matrix components. That enables the utilization of a photon energy unaffecting the matrix components resulting in increased sensitivity due to essentially non-existent background signals. As literature values for many ionization potentials are unavailable, IPs of several security relevant substances were determined using monochromatized synchrotron radiation from BESSY, Germany. All analyzed substances exhibited IPs significantly below the IPs of common matrix molecules such as water, nitrogen and oxygen. First measurements with a pre-demonstrator show that it is possible to shield matrix substances using a well chosen photon energy for soft ionization.

Compact XUV excimer radiation sources and their application

Low energy electron beam excitation of dense helium and neon was used for light production in the extreme ultraviolet (XUV) wavelength range. The entire system was completely filled with the working gas avoiding the use of vacuum equipment for light production, propagation and detection. Emission spectra from He and Ne are dominated by the second continua with peak intensities at 80 and 83 nm, respectively. The hydrogen Lyman-α line was observed as the dominant impurity line. This XUV light source was used for transmission measurements of LiF near its absorption edge.