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To investigate a supposed relationship between exposure by mobile phone base stations and wellbeing, an epidemiological cross sectional study is carried out within the German Mobile Telecommunication Research Program. In a parallel project, a method for the classification of electromagnetic exposure due to mobile phone base stations has been developed. This is based on the results of measurements of high frequency immissions in the interior of more than 1100 rooms and at outdoor locations, the calculation of the emissions of mobile phone antennas under free space propagation conditions and empirically determined transmission factors for the propagation of electromagnetic waves in different types of residential areas for passage of walls and windows. Standard tests (correlation-test, kappa-test, Bland-Altman-Plot, analysis of sensitivity and specificity) show that the method for computational exposure assessment developed in this project is applicable for a first classification of exposures due to mobile phone base stations in epidemiological studies.

A new technique for the analysis of molecular targets with respect to the alignment of the axes of the molecules is described. The ionic fragments from the decay of doubly charged ions created by electron impact are detected in coincidence. From the spatial distribution of the coincidence rate the alignment of the molecular axes can be determined. A rather high degree of alignment has been found in molecular beams from multichannel arrays. A simple model for the explanation of this surprising finding is discussed.

Applicability of a model to estimate radiofrequency electromagnetic field (RF-EMF) strength in households from mobile phone base stations was evaluated with technical data of mobile phone base stations available from the German Net Agency, and dosimetric measurements, performed in an epidemiological study. Estimated exposure and exposure measured with dosemeters in 1322 participating households were compared. For that purpose, the upper 10th percentiles of both outcomes were defined as the 'higher exposed' groups. To assess the agreement of the defined 'higher' exposed groups, kappa coefficient, sensitivity and specificity were calculated. The present results show only a weak agreement of calculations and measurements (kappa values between -0.03 and 0.28, sensitivity between 7.1 and 34.6). Only in some of the sub-analyses, a higher agreement was found, e.g. when measured instead of interpolated geo-coordinates were used to calculate the distance between households and base stations, which is one important parameter in modelling exposure. During the development of the exposure model, more precise input data were available for its internal validation, which yielded kappa values between 0.41 and 0.68 and sensitivity between 55 and 76 for different types of housing areas. Contrary to this, the calculation of exposure-on the basis of the available imprecise data from the epidemiological study-is associated with a relatively high degree of uncertainty. Thus, the model can only be applied in epidemiological studies, when the uncertainty of the input data is considerably reduced. Otherwise, the use of dosemeters to determine the exposure from RF-EMF in epidemiological studies is recommended.

A modular hard- and software package for an automated data acquisition and analysis system based on an IBM PC/AT computer has been developed for use in beam scattering experiments. Due to the high flexibility of the soft- and hardware, modifications allowing applications in other experimental set-ups such as spectrometers or optical spectrometers can easily be performed. An interface for communication with low-level peripherals and software modules for menu-driven control, data collection, storage and analysis is described and an example of the use of the system in a collision experiment is presented.

Detailed information about scattering amplitudes of inelastic atomic collision processes is obtained by simultaneous detection of a scattered particle and a photon emitted from a scattered particle. Channels of neighbouring excitation energy, which are difficult to distinguish by optical or energy loss spectroscopy, are demonstrated to be separable making use of a difference in radiative lifetimes and of the resulting different response to an external magnetic field. The results are discussed in the framework of a quasimolecular description of the collision pair. For the He+ + He system, a complete picture of the process is obtained by modifying models discussed previously. Qualitative conclusions are drawn for the He+ + Ne system.

The mass spectra of doubly charged ions of the hydrocarbon molecules ethene, difluorethene, propane, propene, cyclopropane, propyne, allene, 1,3-butadiene, 2-butene ( cis ), benzene, and cyclohexane have been recorded. For some of them, appearance energies of doubly charged fragments could be measured. In the case of benzene, we even observed the triply charged molecular ion.

The mixing of state multipoles for an atomic state with unresolved fine structure in a magnetic field is investigated in its simplest case: the conversion of alignment to orientation. The combined action of the external field and the spin-orbit coupling results in a build-up of orientation and hence in the emission of circularly polarised light although the excitation process is axially symmetric and is invariant with respect to the reversal of the symmetry axis and thus the system could only show alignment initially. The case investigated is the collisional excitation of the He 33D state by He+ ions. After correction of some errors in the theoretical literature the agreement between the calculated and the observed circular polarisation of the fluorescence radiation from the collisionally excited He atoms is very good. Owing to possible objections in two previous experiments this is the first unambiguous demonstration of the alignment to orientation conversion effect.

The authors have studied the alignment and orientation of the electron cloud of the Li(22P) and He(21P) states excited by 2p sigma -2p pi rotational coupling for impact parameters between 0.2 and 1.1 au in 1-25 keV Li+-He collisions by coherence and correlation analysis techniques. It is found that for collision energies below 5 keV the shape of the excited electron cloud is very nearly that of a p orbital, aligned perpendicular to the asymptotic internuclear axis, independent of impact parameter and of whether the electron stays on the He core or is transferred to the Li centre during the collision. These findings agree with the predictions based on an analysis of the simple diabetic MO diagram for the Li-He system. At energies above 5 keV, the shape changes significantly. Also, the alignment angle deviates from the perpendicular direction, being larger than 90 degrees for Li and smaller for He. The angular momentum perpendicular to the collision plane shows a pronounced variation with collision energy but is only weakly dependent on impact parameter. Possible origins for this behaviour are discussed.

The design and the operating conditions of a new electron bombardment ion source are described. The ion source produces an ion beam with a small kinetic energy spread of 0.1-0.5 eV (full width at half maximum) and a relatively high brightness of up to 50 A sr-1 m-2 for a kinetic energy of 200 eV.

The scattering process He++He(1s2) to He++He(1s2p)1P has been investigated at low (

The design and an example for the application of a very versatile electronic device for the control of the correct operation of a large number of different components in a complex apparatus, and the protection of sensitive equipment, is described. Its main characteristics are the modular structure and the free programming ability of the input and output properties via a diode matrix, allowing the adaptation of the device to virtually any new demand.