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Amorphous and liquid precursors of calcium carbonate are believed to be central species of biomineralization, which serves as an important inspiration for materials chemists in the quest for new and improved organic-inorganic hybrid materials. It has become increasingly clear that magnesium ions exhibit an important function through kinetic stabilization of the metastable precursors. We show that they additionally tune the wettability of liquid precursors of CaCO3, which is a crucial requirement for successful mineralization of proteinaceous organic matrices. Moreover, tunable wettability offers straightforward means to control mineralization sites in organic-inorganic hybrids. © 2013 American Chemical Society.

Controlling a coil-to-helix transition in peptide-polymer conjugates with soft stimuli requires the careful balancing of stabilizing and destabilizing effects in the peptide segment. The transition between two secondary structures of a bioconjugate is realized using calcium ions to establish a biomimetic control mechanism. Regulation of Ca 2+-ion levels via competitive Ca 2+-ion binders made the process reversible. © 2011 The Royal Society of Chemistry.

Crystal-GRID is a new and complementary method for studying interatomic solid state potentials in the energy range 1 eV to 1 keV. Due to a neutron capture induced photon emission an atom of the crystal starts moving with an energy of some hundreds of eV. Information on the movement of this nuclear probe can be read out by measuring the Doppler shift of a second in-flight emitted photon. The amount of information depends strongly on the nuclear level lifetime in between the two photon emissions and on the interatomic interaction. Systematic theoretical investigations will be presented showing under which requirements, e.g. for count rates or lifetimes, interatomic potentials can be investigated. Experimental results for ZnS and TiO2 will be presented. In these cases it was possible to simultaneously extract the nuclear level lifetime and the screening length of the screened Coulomb potential.

Crystal-GRID measurements have been performed with ZnS single crystals. For the first time, an asymmetric Crystal-GRID line shape could be observed. The preliminary data evaluation indicates that the reported lifetime of the 3221 keV level in 33 is too short. A value of about 60 fs has been found. Due to this ``long'' lifetime the line shape is much less structured than calculated with the reported lifetime.

Crystal-GRID is a new and complementary method for studying interatomic solid state potentials in the energy range 1 eV to 1 keV. Due to a neutron capture induced photon emission an atom of the crystal starts moving with an energy of some hundreds of eV. Information on the movement of this nuclear probe can be read out by measuring the Doppler shift of a second in-flight emitted photon. The amount of information depends strongly on the nuclear level lifetime in between the two photon emissions and on the interatomic interaction. Systematic theoretical investigations will be presented showing under which requirements, e.g. for count rates or lifetimes, interatomic potentials can be investigated. Experimental results for ZnS and TiO2 will be presented. In these cases it was possible to simultaneously extract the nuclear level lifetime and the screening length of the screened Coulomb potential.

The Doppler effect of electromagnetic radiation represents a very direct indicator to study the motion of emitting particles. In the Crystal-GRID technique one uses the ultra high resolution power of the crystal spectrometers GAMS4 and GAMS5 to measure the Doppler broadening of $\gamma$ radiation emitted from excited nuclei. Thus it represents a new nuclear probe for the direct study of atomic motion in solids at kinetic energies of several hundreds of eV. A detailed description of the experimental technique will be given together with an overview on already performed experiments using massive single crystals of TiO2, NaCl, Ni and Cr. In these experiments the comparison of experimental data to predictions deduced from Molecular Dynamics simulations has allowed to obtain new repulsive interatomic potentials. The currently used double flat crystal geometry of the spectrometers has allowed to use only massive targets. Recent technical improvements of the GAMS5 spectrometer towards a double bent crystal geometry will allow to extend the technique to studies of crystalline layers as they may result from ion implantation. The current status of the spectrometer and the expected capabilities will be presented.

The Doppler effect of electromagnetic radiation represents a very direct indicator to study the motion of emitting particles. In the Crystal-GRID technique one uses the ultra high resolution power of the crystal spectrometers GAMS4 and GAMS5 to measure the Doppler broadening of $\gamma$ radiation emitted from excited nuclei. Thus it represents a new nuclear probe for the direct study of atomic motion in solids at kinetic energies of several hundreds of eV. A detailed description of the experimental technique will be given together with an overview on already performed experiments using massive single crystals of TiO2, NaCl, Ni and Cr. In these experiments the comparison of experimental data to predictions deduced from Molecular Dynamics simulations has allowed to obtain new repulsive interatomic potentials. The currently used double flat crystal geometry of the spectrometers has allowed to use only massive targets. Recent technical improvements of the GAMS5 spectrometer towards a double bent crystal geometry will allow to extend the technique to studies of crystalline layers as they may result from ion implantation. The current status of the spectrometer and the expected capabilities will be presented.

Crystal-GRID is a new and complementary method for studying interatomic potentials in crystals at intermediate energies between 1 eV and 1 keV. After a neutron capture reaction a first photon emission leads to a recoil of the still excited nucleus. While moving through the crystal a second photon is emitted. When observing many recoil events a structured and Doppler broadened gamma line shape is obtained due to the anisotropic slowing down in the crystal. Experimental findings from the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL are compared to predictions from molecular dynamics (MD) simulations. Thereby information about the interatomic potential can be obtained. Results will be presented for ZnS single crystals, showing that the universal screened Coulomb potentials (ZBL, KrC) are not appropriate in the examined energy region. A new potential for that region will be presented.

In the Crystal-GRID (Gamma Ray induced Doppler Broadening) technique one uses the fact that atomic nuclei can be excited by a thermal neutron capture reaction. The de-excitation process takes place via the emission of gamma-quanta. The emission of the first gamma-quantum after the neutron capture leads to a recoil of the excited nucleus. Typical recoil energies are in the range of several hundreds of eV and therefore much higher than the displacement threshold of the atom. The recoiling atom will start to collide with its neighbours losing successively kinetic energy until thermal energies are reached. During the collision process a second gamma-ray might be emitted by the atomic nucleus and, as the emitter was moving, the energy of the gamma-quantum will be Doppler shifted. The Doppler-shift is a very direct indicator to study the motion of the emitting particle and yields information on the recoil process of the atom. However, due to the isotropic orientation of the recoil direction one observes a Doppler-broadening of the the Intensity distribution I(Eg2). The sensitivity of the technique to the study of atomic collision processes is enhanced if single crystalline targets are used. In this case the microscopic anisotropy of the slowing down process induces a characteristic fine structure of the Doppler-broadened line shapes. Measurements with differently aligned targets with respect to the axis of observation give different line shapes I(Eg2) and allow therefore to accumulate information on the microscopic collision processes. A detailed description of the experimental technique will be given together with an overview on already performed experiments. In these experiments the comparison of experimental data to predictions deduced from Molecular Dynamics simulations has allowed to obtain new repulsive interatomic potentials. Currently, the measurement of I(Eg2) is carried out using a double flat crystal geometry, which allows to obtain a relative energy resolution

Crystal-GRID is a direct method to study orientation-dependent slowing down of recoil atoms in mono-crystals at intermediate recoil velocities of up to 1 Angstrom/fs. The method is based on the excitation of nuclei by neutron capture and their deexcitation by successive photon emissions. A first photon emission leads to a recoil of a few 100 eV. Special deexcitation channels are considered where the recoiling nucleus is not yet at rest when the second photon is emitted. The Doppler shifted energy of this second gamma quantum is measured. When observing many deexcitations a Doppler broadened gamma line shape is obtained. The slowing down of recoiling atoms is anisotropic due to the regular and discrete positions of the collision partners in a lattice. The use of single-crystalline targets allows to observe this anisotropy via a pronounced structure of the Doppler broadened gamma line. As the Doppler shift only depends on the projection of recoil velocities on the axis of observation, different line shapes can be obtained when performing various measurements with crystals aligned differently. Measurements have been carried out with the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL. Doppler broadened line shapes could be obtained using ZnS single crystals in three orientations. They are compared to predictions from molecular dynamics (MD) simulations. Thereby, parameters of classical interatomic potentials describing the slowing down have been extracted. Detailed results will be presented for ZnS, showing that the universal screened Coulomb potentials (ZBL, KrC) have to be modified in the examined energy region. Using the modified potentials, effects such as channelling and blocking have been studied by computer simulations. It will be discussed to which extent the potential corrections are important for simulations of ion beam techniques.

Crystal-GRID is a direct method to study orientation-dependent slowing down of recoil atoms in mono-crystals at intermediate recoil velocities of up to 1 Angstrom/fs. The method is based on the excitation of nuclei by neutron capture and their deexcitation by successive photon emissions. A first photon emission leads to a recoil of a few 100 eV. Special deexcitation channels are considered where the recoiling nucleus is not yet at rest when the second photon is emitted. The Doppler shifted energy of this second gamma quantum is measured. When observing many deexcitations a Doppler broadened gamma line shape is obtained. The slowing down of recoiling atoms is anisotropic due to the regular and discrete positions of the collision partners in a lattice. The use of single-crystalline targets allows to observe this anisotropy via a pronounced structure of the Doppler broadened gamma line. As the Doppler shift only depends on the projection of recoil velocities on the axis of observation, different line shapes can be obtained when performing various measurements with crystals aligned differently. Measurements have been carried out with the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL. Doppler broadened line shapes could be obtained using ZnS single crystals in three orientations. They are compared to predictions from molecular dynamics (MD) simulations. Thereby, parameters of classical interatomic potentials describing the slowing down have been extracted. Detailed results will be presented for ZnS, showing that the universal screened Coulomb potentials (ZBL, KrC) have to be modified in the examined energy region. Using the modified potentials, effects such as channelling and blocking have been studied by computer simulations. It will be discussed to which extent the potential corrections are important for simulations of ion beam techniques.

Crystal-GRID measurements have been performed with ZnS single crystals. A new Crystal-GRID potential could be determined by splining a Stillinger-Weber like equilibrium potential to screened Coulomb potentials. The new potential is fitted to experimental data containing information about the energy range of about 10 to 500 eV and differs significantly from the screened Coulomb potentials. The nuclear level life time of the 3221 keV level in 33S has been determined to be (48.8 +/- 0.7) fs. Furthermore the predicted asymmetry of a Crystal-GRID line shape could be observed for the first time.

Crystal-GRID is a direct method to study orientation-dependent slowing down of recoil atoms in mono-crystals at intermediate recoil velocities of up to 1 Angstrom/fs. The method is based on the excitation of nuclei by neutron capture and their deexcitation by successive photon emissions. A first photon emission leads to a recoil of a few 100 eV. Special deexcitation channels are considered where the recoiling nucleus is not yet at rest when the second photon is emitted. The Doppler shifted energy of this second gamma quantum is measured. When observing many deexcitations a Doppler broadened gamma line shape is obtained. The slowing down of recoiling atoms is anisotropic due to the regular and discrete positions of the collision partners in a lattice. The use of single-crystalline targets allows to observe this anisotropy via a pronounced structure of the Doppler broadened gamma line. As the Doppler shift only depends on the projection of recoil velocities on the axis of observation, different line shapes can be obtained when performing various measurements with crystals aligned differently. Measurements have been carried out with the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL. Doppler broadened line shapes could be obtained using ZnS single crystals in three orientations. They are compared to predictions from molecular dynamics (MD) simulations. Thereby, parameters of classical interatomic potentials describing the slowing down have been extracted. Detailed results will be presented for ZnS, showing that the universal screened Coulomb potentials (ZBL, KrC) have to be modified in the examined energy region. Using the modified potentials, effects such as channelling and blocking have been studied by computer simulations. It will be discussed to which extent the potential corrections are important for simulations of ion beam techniques.

Crystal-GRID is a direct method to study orientation-dependent slowing down of recoil atoms in mono-crystals at intermediate recoil velocities of up to 1 Angstrom/fs. The method is based on the excitation of nuclei by neutron capture and their deexcitation by successive photon emissions. A first photon emission leads to a recoil of a few 100 eV. Special deexcitation channels are considered where the recoiling nucleus is not yet at rest when the second photon is emitted. The Doppler shifted energy of this second gamma quantum is measured. When observing many deexcitations a Doppler broadened gamma line shape is obtained. The slowing down of recoiling atoms is anisotropic due to the regular and discrete positions of the collision partners in a lattice. The use of single-crystalline targets allows to observe this anisotropy via a pronounced structure of the Doppler broadened gamma line. As the Doppler shift only depends on the projection of recoil velocities on the axis of observation, different line shapes can be obtained when performing various measurements with crystals aligned differently. Measurements have been carried out with the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL. Doppler broadened line shapes could be obtained using ZnS single crystals in three orientations. They are compared to predictions from molecular dynamics (MD) simulations. Thereby, parameters of classical interatomic potentials describing the slowing down have been extracted. Detailed results will be presented for ZnS, showing that the universal screened Coulomb potentials (ZBL, KrC) have to be modified in the examined energy region. Using the modified potentials, effects such as channelling and blocking have been studied by computer simulations. It will be discussed to which extent the potential corrections are important for simulations of ion beam techniques.

In the Crystal-GRID (Gamma Ray induced Doppler Broadening) technique one uses the fact that atomic nuclei can be excited by a thermal neutron capture reaction. The de-excitation process takes place via the emission of gamma-quanta. The emission of the first gamma-quantum after the neutron capture leads to a recoil of the excited nucleus. Typical recoil energies are in the range of several hundreds of eV and therefore much higher than the displacement threshold of the atom. The recoiling atom will start to collide with its neighbours losing successively kinetic energy until thermal energies are reached. During the collision process a second gamma-ray might be emitted by the atomic nucleus and, as the emitter was moving, the energy of the gamma-quantum will be Doppler shifted. The Doppler-shift is a very direct indicator to study the motion of the emitting particle and yields information on the recoil process of the atom. However, due to the isotropic orientation of the recoil direction one observes a Doppler-broadening of the the Intensity distribution I(Eg2). The sensitivity of the technique to the study of atomic collision processes is enhanced if single crystalline targets are used. In this case the microscopic anisotropy of the slowing down process induces a characteristic fine structure of the Doppler-broadened line shapes. Measurements with differently aligned targets with respect to the axis of observation give different line shapes I(Eg2) and allow therefore to accumulate information on the microscopic collision processes. A detailed description of the experimental technique will be given together with an overview on already performed experiments. In these experiments the comparison of experimental data to predictions deduced from Molecular Dynamics simulations has allowed to obtain new repulsive interatomic potentials. Currently, the measurement of I(Eg2) is carried out using a double flat crystal geometry, which allows to obtain a relative energy resolution

Crystal-GRID is a new and complementary method for studying interatomic potentials in crystals at intermediate energies between 1 eV and 1 keV. After a neutron capture reaction a first photon emission leads to a recoil of the still excited nucleus. While moving through the crystal a second photon is emitted. When observing many recoil events a structured and Doppler broadened gamma line shape is obtained due to the anisotropic slowing down in the crystal. Experimental findings from the high-precision gamma spectrometers GAMS 4 and GAMS 5 at the ILL are compared to predictions from molecular dynamics (MD) simulations. Thereby information about the interatomic potential can be obtained. Results will be presented for ZnS single crystals, showing that the universal screened Coulomb potentials (ZBL, KrC) are not appropriate in the examined energy region. A new potential for that region will be presented.

Crystal-GRID measurements have been performed with ZnS single crystals. A new Crystal-GRID potential could be determined by splining a Stillinger-Weber like equilibrium potential to screened Coulomb potentials. The new potential is fitted to experimental data containing information about the energy range of about 10 to 500 eV and differs significantly from the screened Coulomb potentials. The nuclear level life time of the 3221 keV level in 33S has been determined to be (48.8 +/- 0.7) fs. Furthermore the predicted asymmetry of a Crystal-GRID line shape could be observed for the first time.

Crystal-GRID measurements have been performed with ZnS single crystals. For the first time, an asymmetric Crystal-GRID line shape could be observed. The preliminary data evaluation indicates that the reported lifetime of the 3221 keV level in 33 is too short. A value of about 60 fs has been found. Due to this ``long'' lifetime the line shape is much less structured than calculated with the reported lifetime.

Crystal-GRID measurements have been performed with ZnS single crystals. For the first time, an asymmetric Crystal-GRID line shape could be observed. The preliminary data evaluation indicates that the reported lifetime of the 3221 keV level in 33 is too short. A value of about 60 fs has been found. Due to this ``long'' lifetime the line shape is much less structured than calculated with the reported lifetime.