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The Physikalisch-Technische Bundesanstalt (PTB) is the national metrology institute of the Federal Republic of Germany and has been using synchrotron radiation (SR) for more than 40 years. Starting at the former facility BESSY I, the storage ring BESSY II (see corresponding article in this volume) has been used for this purpose since 1998, especially in the X-ray range, as well as PTB's own metrology light source (MLS) for lower photon energies since 2008. Both facilities are located in Berlin-Adlershof and are operated by the Helmholtz-Zentrum Berlin within the framework of contractual agreements with PTB. The basic motivation of the work is radiometry. The two storage rings MLS and BESSY II are used as primary source standards and cryogenic radiometers as primary detector standards. The article gives a brief overview of the present status, scientific highlights, the technological development and upgrade plans for the decade 2023–2033 as well as a perspective of next scientific challenges.

Metalation and self‐metalation reactions of porphyrins on oxide surfaces have recently gained interest. The mechanism of porphyrin self‐metalation on oxides is, however, far from being understood. Herein, we show by a combination of results obtained with scanning tunneling microscopy, photoemission spectroscopy, and DFT computations, that the self‐metalation of 2H‐tetraphenylporphyrin on the surface of ultrathin MgO(001) films is promoted by charge transfer. By tuning the work function of the MgO(001)/Ag(001) substrate, we are able to control the charge and the metalation state of the porphyrin molecules on the surface., The self‐metalation of 2H‐tetraphenylporphyrin on the surface of MgO is believed to be feasible only at defect sites. It is shown that this reaction is promoted by charge transfer and does not necessarily require the presence of defects. Using ultrathin MgO films as substrate and tuning its work function allows the charge and metalation state of the adsorbed molecules to be controlled.

Science advances 8(29), eabn0819 (2022). doi:10.1126/sciadv.abn0819, Published by American Association for the Advancement of Science, Washington, DC [u.a.]

ACS nano 16(10), 17435-17443 (2022). doi:10.1021/acsnano.2c08631, Published by American Chemical Society, Washington, DC

The 3D printing technology has gained ground due to its wide range of applicability. The development of new conductive filaments contributes significantly to the production of improved electrochemical devices. In this context, we report a simple method to producing an efficient conductive filament, containing graphite within the polymer matrix of PLA, and applied in conjunction with 3D printing technology to generate (bio)sensors without the need for surface activation. The proposed method for producing the conductive filament consists of four steps: (i) mixing graphite and PLA in a heated reflux system; (ii) recrystallization of the composite; (iii) drying and; (iv) extrusion. The produced filament was used for the manufacture of electrochemical 3D printed sensors. The filament and sensor were characterized by physicochemical techniques, such as SEM, TGA, Raman, FTIR as well as electrochemical techniques (EIS and CV). Finally, as a proof-of-concept, the fabricated 3D-printed sensor was applied for the determination of uric acid and dopamine in synthetic urine and used as a platform for the development of a biosensor for the detection of SARS-CoV-2. The developed sensors, without pre-treatment, provided linear ranges of 0.5-150.0 and 5.0-50.0 μmol L

Alcoholic beverages contaminated with scopolamine (SCP) are often employed for criminal purposes due to their sedative effect. The determination of the residual levels of SCP in body fluids (e.g., urine) can help to track possible victims of induced ingestions. Biological sample analysis usually requires a preconcentration step to enhance their detectability and to provide sample clean-up. Molecularly imprinted polymers (MIPs) in lieu of conventional solid sorbents represent an enhancement of selectivity, due to their specific recognition sites. Additionally, the adaptation of the solid-phase extraction (SPE) cartridge into a disposable pipette tip extraction (DPX) contributes to the miniaturization of the sample preparation step. Herein, an analytical method for the determination of SCP in synthetic urine samples via the integration of molecularly imprinted solid-phase extraction (MISPE) with DPX as a preconcentration step prior to capillary electrophoresis analysis (also known as MISPE-DPX-CE) is presented. The extraction and elution steps were optimized using a factorial design. Using the optimized conditions, a preconcentration factor of 20 was obtained, leading to a working range of 0.5–6 µM with LOD of 0.04 µM and repeatability of 6.4% (n = 7) and adequate recovery values (84 and 101%) The proposed MISPE-DPX-CE approach was successfully applied to selective extraction, preconcentration, and determination of SCP in synthetic urine samples.

ACS nano 14(11), 15766-15775 (2020). doi:10.1021/acsnano.0c06798, Published by American Chemical Society, Washington, DC

The radiant intensity of synchrotron radiation can be accurately calculated with classical electrodynamics. This primary realization of the spectral radiant intensity has been used by PTB at several electron storage rings which have been optimized to be operated as primary source standards for the calibration of transfer sources in the spectral range of UV and VUV for almost 30 years. The transfer sources are compared to the primary source standard by means of suitable wavelength-dispersive transfer stations. The spectral range covered by deuterium lamps, which represent transfer sources that are easy to handle, is of particular relevance in practice. Here, we report on developments in the realization and preservation of the radiometric scales for spectral radiant intensity and spectral radiance in the wavelength region from 116 nm to 400 nm, based on a set of deuterium reference lamps, over the last few decades. An inside view and recommendations on the operation of the D2 lamps used for the realization of the radiometric scale are presented. The data has been recently compiled to illustrate the chronological behaviour at various wavelengths. Moreover, an overview of the internal and external validation measurements and intercomparisons is given.

Parameter identification problems can be formulated as equations In many interesting cases, X and Y are infinite-dimensional spaces of functions – this was so for all model problems presented in Chap. 1 Although we generally suppose that a unique solution \(u^{{\ast}}\in \mathbb{U}\) exists, explicit formulae for its computation are only rarely available, so that one has to be satisfied with the construction of an approximate solution by numerical methods. In practice, not even the equation T(u) = w itself is perfectly known, if w is a function. Rather, an approximation of w has to be constructed on the basis of a finite number of (inexact) measurements (observations).

Beilstein journal of nanotechnology 11, 1492-1503 (2020). doi:10.3762/bjnano.11.132, Published by Beilstein-Institut zur Förderung der Chemischen Wissenschaften, Frankfurt, M.

Journal of synchrotron radiation 26(4), 1092 - 1100 (2019). doi:10.1107/S1600577519005174, A novel X-ray gas monitor (XGM) has been developed which allows the measurement of absolute photon pulse energy and photon beam position at all existing and upcoming free-electron lasers (FELs) over a broad spectral range covering vacuum ultraviolet (VUV), extreme ultraviolet (EUV) and soft and hard X-rays. The XGM covers a wide dynamic range from spontaneous undulator radiation to FEL radiation and provides a temporal resolution of better than 200 ns. The XGM consists of two X-ray gas-monitor detectors (XGMDs) and two huge-aperture open electron multipliers (HAMPs). The HAMP enhances the detection efficiency of the XGM for low-intensity radiation down to 10$^5$ photons per pulse and for FEL radiation in the hard X-ray spectral range, while the XGMD operates in higher-intensity regimes. The relative standard uncertainty for measurements of the absolute photon pulse energy is well below 10%, and down to 1% for measurements of relative pulse-to-pulse intensity on pulses with more than 10$^{10}$ photons per pulse. The accuracy of beam-position monitoring in the vertical and horizontal directions is of the order of 10 µm., Published by Wiley-Blackwell, Chester

X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation V : [Proceedings] - SPIE, 2019. - ISBN 97815106274209781510627437 - doi:10.1117/12.2520827 X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation, Prague, Czech Republic, 1 Apr 2019 - 4 Apr 2019; SPIE 1103810 pp. (2019). doi:10.1117/12.2520827, The absolute power of the Linac Coherent Light Source pulses has been measured accurately in the hard X-raybeamline by using simultaneously two detectors:1 an X-ray Gas Monitor Detector (XGMD)2 in tandem witha radiometer.3 From these measurements, we were also able to characterize and calibrate in details our setsof beamline attenuators, in addition to extending an absolute calibration for our beamline intensity monitors.Similarly, we demonstrate that commercial optical power meter has a response in the hard X-ray regime, thatcan be cross-correlated with the absolute power of the LCLS beam., Published by SPIE

Journal of synchrotron radiation 26(2), 320 - 327 (2019). doi:10.1107/S1600577519000250, Published by Wiley-Blackwell, [S.l.]

Review of scientific instruments 89(10), 103114 (2018). doi:10.1063/1.5046923, At the Metrology Light Source (MLS), the compact electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB) with a circumference of 48 m, a specific operation mode with two stable closed orbits for stored electrons was realized by transverse resonance island buckets. One of these orbits is closing only after three turns. In combination with single-bunch operation, the new mode was applied for electron time-of-flight spectroscopy with an interval of the synchrotron radiation pulses which is three times the revolution period at the MLS of 160 ns. The achievement is of significant importance for PTB’s future programs of angular-resolved electron spectroscopy with synchrotron radiation and similar projects at other compact electron storage rings. The scheme applied here for selecting the photons originating from a particular orbit by optical imaging has been used before in fs slicing applications and may be relevant for the BESSY VSR project of the Helmholtz-Zentrum Berlin., Published by American Institute of Physics, [S.l.]

The index of refraction and the extinction coefficient for thin films of boron carbide were determined by angle-dependent reflectance measurements in the vacuum-ultraviolet spectral range. The numerical approximation was done using transfer-matrix formalism in combination with particle swarm optimization for the fitting algorithm. By this, not only for the reflectance measurement but also for the numerical approximation, a profound uncertainty budget was developed. This includes possible effects due to contamination and intermediate layers. Thus it was possible to establish a method for determination of n and k with reliable and highly traceable uncertainties, and to significantly improve the consistency of existing data required for current developments in optical technology.

Flying glass fragments are one of the main causes of casualties and injuries during terror attacks with explosives, due to fragments shooting through the air. A common way to increase the blast security in windows is to add a laminate or an interlayer between two or more glass panes creating laminated glass. One of the goals of the interlayer is to prevent fragments from loosening, through adhesive properties in the laminate glass connection. In the construction of the new governmental complex in Oslo, Norway, laminated glass windows are to be used as a measure to increase blast security. The numerical modelling of laminated glass has proven to be challenging. This thesis aims to increase the understanding of laminated glass properties and the response during quasi-static and blast loading. A study of the possibilities and limitations of numerical modelling of laminated glass in quasi-static and blast loading simulations was also conducted in the thesis. Point tracking DIC analysis was used to capture the response in the specimens subjected to blast load Experiments were conducted in the SIMLab research facilities at NTNU. Four-point bending tests were carried out on laminated glass specimens to study the fracture strength during quasi-static loading, and blast tests were conducted on both regular float glass and laminated glass in the SIMLab shock tube to study the response during blast loading. The data recorded during the experiments were interpreted, and the results were used in the development of numerical models of the experiments. The tests were modelled with an explicit non-linear FEM code in IMPETUS Afea Solver, with node splitting used to describe fracture. Parameter studies were conducted to examine the effect of e.g. mesh size, element type and properties of interaction between PVB and glass. From the quasi-static bending tests, it was found that the fracture stresses in the glass varied due to stochastic material properties in float glass. It was found a higher fracture strength in larger samples than the small samples. In the blast tests, the fragment size was smaller in the laminated glass than in the float glass. In the numerical modelling of the glass panes, it was found that node splitting and pentahedron elements gave good results describing crack propagation. Material modelling of the PVB in IMPETUS and interaction between glass and PVB proved challenging and needs further research.

The Physikalisch-Technische Bundesanstalt (PTB) has set up the 630?MeV electron storage ring Metrology Light Source (MLS) in close cooperation with the Helmholtz-Zentrum Berlin (HZB). This electron storage ring has been in regular user operation since April 2008. It is dedicated to synchrotron-radiation-based metrology and technological developments in the far-IR/THz, IR, UV, VUV and EUV spectral ranges, with the use as primary source standard as the key activity. In a permanent process of improvement, the storage ring itself was optimized regarding its regular performance (beam current and lifetime) as well as for special operations (e.g. variable electron energies and electron bunch lengths). The measurement capabilities at the seven different beamline ports were set up sequentially, first in the UV/VUV and IR spectral ranges. This first phase of instrumentation set-up will be finished in 2011 by completing the beamlines for EUV metrology, for the calibration of radiation sources and for the application of undulator radiation.

We report on a successful bilateral intercomparison between the Physikalisch-Technische Bundesanstalt (PTB) and the National Institute of Standards and Technology (NIST). In both laboratories deuterium lamps were calibrated using the calculability of synchrotron radiation. However, the methods applied in the two laboratories differed significantly. Whereas the calibrations at PTB were performed in vacuum and led to spectral radiant intensities, the measurements at NIST were done in air and resulted in spectral irradiances. Therefore, for this bilateral comparison we not only proved the equivalence of the two measurement procedures, but also the validity of the conversion between the different spectro-radiometric quantities. This successful comparison re-establishes the usefulness of deuterium lamps as transfer standards in the ultraviolet spectral range.

The spectral radiant intensity of synchrotron radiation from electron storage rings can be calculated from basic electrodynamic relations (Schwinger equation). A storage ring can, thus, be used as a radiometric primary source standard. The Metrology Light Source (MLS), the dedicated electron storage ring of the Physikalisch-Technische Bundesanstalt, can be operated as a primary radiation source standard from the near infrared up to the soft x-ray region and its operational parameters can be adjusted and accurately measured in a wide range. The MLS electron beam current can be varied from 1 pA (one stored electron) up to 200 mA and, thus, the radiant intensity, being directly proportional to the stored current, can be varied by more than 11 decades. The electron energy, which has a large effect on the spectral shape of the spectrum, can be varied from 105 MeV up to 630 MeV. For the radiometric comparison, the total power irradiated into a well-defined solid angle was directly measured by a cryogenic radiometer as a primary detector standard and compared with the power calculated from the storage ring parameters. These measurements were performed for various electron energies in the range from 200 MeV to 630 MeV, thus varying the shape of the spectrum. For each electron energy setting, the power level was varied within the dynamic range of the cryogenic radiometer by a variation of the electron beam current. Good agreement was found for all parameter settings, thus validating the performance of the cryogenic radiometer and the storage ring parameter measurements within the related uncertainty budget.

The absolute single-shot pulse energy of the SPring 8 extreme ultraviolet (EUV) free electron laser (FEL) was measured using a cryogenic radiometer with a relative standard uncertainty of 3%. The temperature change of the cavity in the cryogenic radiometer caused by an incident FEL pulse was determined using a lock-in amplifier and an ac Wheatstone bridge. The measured pulse energies were compared with a gas-monitor detector developed by Physikalisch-Technische Bundesanstalt/Deutsches Elektronen-Synchrotron/Ioffe Physico-Technical Institute (Ioffe) at a wavelength of 51.3 nm at the SPring-8 EUV-FEL in a shot-to-shot mode. The pulse energies measured using the two detectors agree within 2.0%.

The photoionization cross sections for atomic He, Ne, Ar, Kr and Xe were determined with a double ionization chamber using monochromatized synchrotron radiation from the electron storage ring Metrology Light Source in the wavelength range from 25 to 90 nm. Particular attention was paid to full traceability to the SI units, and thus to achieve reliably small measurement uncertainties, i.e. in the sub-percent range throughout most of the investigated spectral range. Thus, we basically substantiated already existing data, however now with pointwise (i.e. non-interpolated) data and reduced uncertainties. The data is of great benefit for rare gas photoionization-based radiometric standards in numerous applications, e.g. space-based ionization chamber measurements, gas monitor detectors for free electron lasers, or future SI traceable gas analytics.

International audience; The investigation of some solar radiations of interest for astrophysicists requires optics in the 80–130 nm vacuum ultra-violet spectral range (VUV). In this domain, where both transmittance and reflectance of most materials are very low, the measurement of optical constants is specifically difficult, and optical data are consequently often either inexistent or uncertain. Reliable modelling of optical components for VUV, like polarizing multi-layered mirrors, necessitates prior measurement of complex indices of the thin films involved in the coating. Fluorides like MgF2 or AlF3 are among the rare materials capable to contribute to multi-layer mirrors in the VUV. We have determined optical constants of thin films of these two materials by using a two media reflectance method at normal incidence and a graphical determination particularly suited to this VUV region, which we presented in a previous paper. Optical constants are determined in the range 60–124 nm with 2 nm step, and are compared to existing data. On the basis of these measured indices, polarizing mirrors for k1 = 121.6 nm or k2 = 103.2 nm have been modelled and fabricated. Their reflectance measured versus incidence angle by using monochromatized synchrotron radiation at the above wavelengths is found in agreement with the calculated predictions.

A fluid conducting composite material prepared from graphite powder, commercial epoxy resin Araldite®, and cyclohexanone has been developed. The composition was optimized considering the mechanical properties as conductivity and adhesiveness using response surface methodology. This work employed cyclic voltammetry and amperometry to investigate the characteristics of such composite electrodes without and with the insertion of Prussian blue in the electrode body (bulk modified electrode). The composite electrodes were also successfully used for the amperometric detection of hydrogen peroxide at 0.0V vs Ag/AgCl.

Future missions for space astronomy and solar research require innovative vacuum ultraviolet (VUV) photodetectors. Present UV and VUV detectors exhibit serious limitations in performance, technology complexity and lifetime stability. New developments of metal-semiconductor-metal (MSM) solar-blind photodetectors based on diamond, cubic boron nitride (c-BN), and wurtzite aluminum nitride (AlN) are reported. In the wavelength range of interest. the characteristics of the MSM photodetectors present extremely low dark current. high breakdown voltage. and good responsivity. Diamond, c-BN, and AlN MSM photodetectors are sensitive and stable under UV irradiation. They show a 200 nm to 400 nm rejection ratio of more than four orders of magnitude and demonstrate the advantages of wide band gap materials for VUV radiation detection in space. (C) 2008 Elsevier B.V. All rights reserved.

FLASH, the free electron laser at DESY in Hamburg, is the first facility of its kind providing intense, femtosecond radiation pulses in the vacuum ultraviolet and soft X-ray range for user experiments. A broad science program has been started in summer 2005 with applications in atomic and molecular physics, cluster physics, the study of warm dense matter and surface dynamics, and diffraction imaging of small structures and biological samples with nanometer resolution. A selection of first experimental results is highlighted in this paper.

The discretization of linear identification problems led to linear systems of algebraic equations. In case a solution does not exist, these can be replaced by linear least squares problems, as already done in Sect. 2.3 We will give a detailed sensitivity analysis of linear least squares problem and introduce their condition number as a quantitative measure of ill-posedness. If the condition of a problem is too bad, it can not be solved practically. We introduce and discuss the concept of regularization which formally consists in replacing a badly conditioned problem by a better conditioned one. The latter can be solved reliably, but whether its solution is of any relevance depends on how the replacement problem was constructed. We will especially consider Tikhonov regularization and iterative regularization methods. The following discussion is restricted to the Euclidean space over the field of real numbers \(\mathbb{K} = \mathbb{R}\), but could easily be extended to complex spaces.

Nonlinear inverse problems are much more difficult to solve than linear ones and the corresponding theory is far less developed. Each particular problem may demand a specific regularization. Nevertheless, one can formulate and analyze basic versions of nonlinear Tikhonov regularization and nonlinear iterative methods, which will be done in Sects. 4.1 and 4.6, respectively. These basic versions serve as starting points for regularizations adapted to our nonlinear model problems (Sects. 4.2, 4.5, and 4.6). Nonlinear Tikhonov regularization leads to nonlinear least squares problems. Sections 4.3 and 4.4 present algorithms to solve these numerically.

In Sect. 1.1 we present four typical examples of inverse problems from physics and engineering and already give an idea of why these problems can be difficult to solve in practice. In all examples causes as well as effects are functions. Therefore, any useful notion of inverse problems as equations relating causes to effects must be general enough to include equations in function spaces, like differential and integral equations. Section 1.2 begins with an informal introduction of function spaces by way of an example, a more formal introduction being outsourced to Appendix B. Later in this section we indeed describe inverse problems as equations in vector spaces and define “ill-posedness”, which is the primary concern when dealing with inverse problems. In Sects. 1.3 and 1.4, we formulate four model problems from inverse gravimetry and seismic tomography, which will be taken up in later chapters to illustrate the methods presented in this book.