Dipolar Relaxation Research Articles

Multiscale analysis of dislocation loops and voids in tungsten

We performed ab initio density functional theory simulations of $\frac{1}{2}\ensuremath{\langle}111\ensuremath{\rangle}$ interstitial dislocation loops, closed and open vacancy loops, $\ensuremath{\langle}100\ensuremath{\rangle}$ interstitial loops, and voids in tungsten, using simulation cells involving from 2000 to 2700 atoms. The size of the loops transcends the microscopic scale and reaches the mesoscopic scale where asymptotic elasticity treatment applies. Comparing the formation energies of dislocation vacancy loops and voids, we conclude that a void remains the most energetically favorable vacancy defect over the entire range of sizes investigated here. A closed $\frac{1}{2}\ensuremath{\langle}111\ensuremath{\rangle}$ vacancy loop is more stable than an open loop if the number of vacancies in the loop is greater than $\ensuremath{\sim}45$, corresponding to the diameter of a loop of approximately 1.8 nm. We have also computed elastic dipole tensors and relaxation volumes of loops and voids, representing the source terms in continuum models for radiation induced stresses and strains in the material. A detailed analysis of metastable configurations of closed and open vacancy loops performed using molecular statics simulations shows that vacancy loop configurations are not unique, and significant fluctuations of defect structures may occur in the course of microstructural evolution under irradiation.

Effect of cholesterol on the hydration properties of ester and ether lipid membrane interphases

Fluorescence spectroscopy and Molecular Dynamics results show that cholesterol reduces water along the chains in ether lipids by changing the water distribution pattern between tightly and loosely bound water molecules. Water distribution was followed by emission spectra and generalized polarization of 6-dodecanoyl-2-dimethyl aminonaphthalene (Laurdan) inserted in 1,2-dimiristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-di-O-tetradecyl-sn-glycero-3-phosphocholine (14: 0 Diether PC) membranes. Molecular Dynamics simulations indicate that the action of cholesterol could be different in ether PC in comparison to ester PC. In addition, Cholesterol seems to act “per se” as an additional hydration center in ether lipids.Regardless of the phase state, cholesterol both in DMPC and 14:0 Diether PC vesicles, changed the distribution of water molecules decreasing the dipole relaxation of the lipid interphase generating an increase in the non-relaxable population. Above 10% Cholesterol/14:0 Diether PC ratio vesicles' interphase present an environment around Laurdan molecules similar to that corresponding to ester PC.

Investigations on the effect of ageing on charge de‐trapping processes of epoxy–alumina nanocomposites based on isothermal relaxation current measurements

In this study, the relationship between thermal ageing and charge trapping properties of epoxy-based nanocomposites has been investigated. With ageing, any dielectric material undergoes thorough degradation. This degradation significantly affects the space charge accumulation and charge trapping behaviour of the dielectric, which are very important parameters for insulation health under high-voltage direct current (HVDC) environment. In this work, an improved model based on the isothermal relaxation current (IRC) has been developed to study the charge trapping behaviour of pure epoxy and epoxy alumina (Al2 O3) nano-composites at different ageing conditions. A methodology based on polarisation–depolarisation current (PDC) measurements has been proposed to identify the current component due to a dipolar relaxation in measured total IRC. This will help to identify the trap distribution characteristics more accurately compared to conventional IRC measurements. It was experimentally observed that the addition of nanoparticles significantly reduces trapped charge formation and reduces thermal degradation. It is observed that aging leads to the generation of deeper traps, while the addition of Al2 O3 nanoparticles mainly enhances the density of shallow traps. Results presented in this work indicate that epoxy–alumina nanocomposites are very much suitable in HVDC applications from the perspective of trapped charge accumulation.

Not So Far, Not So Close: A Configurational Study of a Carbon Nanotube Bundle for Better Dielectric Phenomena

Size of pores or spacing among nano‐protrusions such as nanotubes on an electrode surface greatly affects diffusive, viscous, and dielectric phenomena of electrolyte through openings. In this study, a configurational study was conducted to examine the effect of spacing among the single‐walled carbon nanotubes on dielectric and viscous phenomena. Behavior of a polar liquid, acetonitrile, was investigated by molecular simulations at two low densities. Results show that viscosity of the liquid is greatly enhanced by interaction with closely packed tubes' bundle. In conjunction with such increase in viscosity, relaxation of dipoles takes longer times inside such closed packed bundle. Most importantly, spacing among the tubes with diameter D should be at about D/2 in a direction for better dielectric phenomena.

Investigation of magnetic and ferroelectric properties along with the magnetoelectric coupling behavior for asserting a room temperature bi-phase composite as multiferroics

Various composites of nominal composition (1-x)Ba0.95Ca0.05TiO3 + xLi0.1Cu0.1Co0.1Zn0.6Fe2.1O4 have been prepared and studied thoroughly. X-ray diffraction and Rietveld refinement confirmed the presence of Ba0.95Ca0.05TiO3 and Li0.1Cu0.1Co0.1Zn0.6Fe2.1O4 phases in the composites. The microstructures have been investigated by field emission scanning electron microscopy. Temperature dependent dielectric constant shows two peaks, one is at 150 °C and another at 270 °C for x = 0.10 composite which resembles the characteristic ferroelectric and ferromagnetic transition peaks. A gradual progression of ferro-para electric transition towards room temperature is observed with doping. The non-Debye type dipole relaxations have been found. The linearity in the log(σAC) vs. log(ω) plots indicate that conduction is due to small polaron hopping. The real part of initial permeability increases with growing ferrite concentration but the cut-off frequency decreases. The magnetic property is also enhanced with doping content. The typical ferroelectric hysteresis loops have also seen with the addition of Li0.1Cu0.1Co0.1Zn0.6Fe2.1O4 up to x = 0.40. The impedance values are found to decreases in the Nyquist plots. The magnetoelectric voltage coefficient is obtained 287 × 103 V/mT for x = 0.15 at room temprrature. We found both ferromagnetic and ferroelectric hysteresis loops at room temperature. So, it confirms that the composites exhibit room temperature multiferroicity. This type of composites offers variety of opportunity for multifunctional devices application like hetero-structured read / write memory devices, switching devices and magnetic field sensing devices.

Relaxation dynamics associated with the multiple polymorphic phase transitions in morphotropic phase boundaries BiScO3-PbTiO3 solid solutions

High temperature electrical properties of morphotropic phase boundary BiScO3-PbTiO3 compositions, exhibiting high piezoelectric coefficient, saturation polarization, field induced strain and low dielectric loss have been presented in detail. Dielectric loss and various electrical parameters have been comprehensively utilized to identify multiple dipolar relaxation dynamics in the regime where conductivity effects are low. Dielectric data confirms presence of various polymorphs exhibiting lower (higher) symmetry configuration, which extends to wider (narrower) temperature regime. Effect of conductivity associated with the charge transport is not dominant up to 600 K, which shows that this material is a promising candidate for high temperature applications.

Probing relaxation models by means of Fast Field-Cycling relaxometry, NMR spectroscopy and molecular dynamics simulations: Detailed insight into the translational and rotational dynamics of a protic ionic liquid

A combination of temperature dependent Fast Field-Cycling (FFC) relaxometry and high-resolution NMR spectroscopy provides more than five orders of magnitude in frequency range for studying translational and rotational dynamics of ionic liquids. However, to make use of this broad frequency range, certain requirements have to be met: The viscosity of the liquid has to be of the right order of magnitude, and the material has to exhibit a sufficiently broad liquid range. In addition, NMR sensitive nuclei have to be present (ideally) on both, cation and anion, and appropriate relaxation models properly describing the molecular dynamics have to be available. For the latter, Molecular Dynamics (MD) simulations are ideally suited to suggest meaningful relaxation models. In this study we employ the protic ionic liquid triethylammonium bis(trifluoromethylsulfonyl)-imide [TEA][NTf2] as model compound to gain insight into details of the molecular dynamical processes. By addressing different NMR sensitive nuclei on both ions, 1H nuclei on the triethylammonium cation, and 19F on the NTf2 anion, we are able to obtain translational dynamics as well as rotational dynamics for both species at the same time. The obtained temperature dependent translatoric diffusion coefficients are consistent with our MD simulations, and are found to be in agreement with data reported in the literature. In addition, two types of NMR relaxation processes are employed to investigate the intramolecular relaxation: (1) dipolar relaxation at low frequencies (employing FFC) addressing 1H and 19F nuclei, and (2) quadrupolar relaxation at high frequencies addressing 2H nuclei. In near quantitative agreement with MD simulations, we show that both, dipolar relaxation obtained via FFC and quadrupolar relaxation obtained via high-field NMR are leading to consistent rotational correlation times, suggesting that the rotational motion of the cation is dominantly isotropic. Hence, the intramolecular 1H relaxation rate of the cation determined via FFC can be appropriately expressed by a single rotational correlation time, compatible with the Bloembergen Purcell Pound (BPP) approach. MD simulations of the NTf2 anion, however, suggest that its reorientational dynamics is strongly anisotropic. Consequently, the proper description of the intramolecular 19F relaxation rate of the anion requires a more complex model beyond the BPP approach employing at least two correlation times: By taking internal rotation of the CF3 groups into account, we are able to determine correlation times compatible with our MD simulations.

Physical Model for Frequency Domain Spectroscopy of Oil–Paper Insulation in a Wide Temperature Range by a Novel Analysis Approach

Frequency domain spectroscopy is considered to be a promising and novel method for the assessment of the insulation condition of power equipment. This work has practical significance as it explains the microscopic mechanism of this method in a wide temperature range and further establishes its quantitative model. To achieve this, in the present paper, we select oil-impregnated paper—one of the most common insulation materials for power equipment with a complex microstructure—as a test sample, deduce a formula based on the relationship between the real and imaginary parts of the complex permittivity to extract the spectra of independent dielectric processes and measure the frequency domain spectra of oil-impregnated paper under different temperatures, as well as its thermally stimulated depolarization current with a series of bias voltages. The analysis results reveal that oil-impregnated paper’s frequency domain spectra in a wide temperature range are mainly determined by dielectric processes whose generation mechanisms are low-frequency dispersion, DC conduction, electrode relaxation, interfacial relaxation and dipole relaxation, respectively. Moreover, due to the different thermal properties of charge motions, the macroscopic characteristics and microscopic generation mechanisms of both spectra vary significantly with the sample’s temperature. After verifying the generation mechanisms of the spectra in high, middle and low-temperature ranges, function models for those spectra with clear physical meanings are established separately, providing sufficient physical parameters to carry out insulation assessment.

Electrical Properties Study of Solid Polymer Electrolyte based on PolyCaproLactone/LiCF3SO3 Added Plasticizer

The electrical properties of solid polymer electrolyte based on biodegradable polymer PolyCaproLactone (PCL)/LiCF3SO3 with PC plasticizer addition have been studied. Polymer electrolyte membranes were prepared by solution casting technique by varying propylene carbonate (PC) composition (0-60) % weight. The membranes were characterized by the Electrical Impedance Spectroscopy at room temperature to measure its ionic conductivity and other electrical properties such as dielectric constant and tangent loss. The PCL/LiCF3SO3 system containing 20% weight PC plasticizer exhibits the highest conductivity of 4.92 x 10−4 S/cm at room temperature. The dielectric constant shows decreases with frequency increasing and it depends on dissociation of ions in the polymer electrolyte system. The tangent loss suggests that there are relaxing dipoles in the polymer electrolyte that shift toward higher frequency region. The membrane microstructure also investigated by XRD and the result showed that the PC plasticizer made the PCL/LiCF3SO3 system become more amorphous

Dielectric relaxation behavior and overlapping large polaron tunneling conduction mechanism in NiO–PbO μ-cauliflower composites

The NiO–PbO μ-cauliflower composites was synthesized via glycine assisted self-ignition techniques with an objective to investigate its temperature evolving distinct dielectric relaxor behavior and alternating current conduction mechanism, for exploring its application as high energy storage devices. The x-ray diffraction and Raman spectroscopy was utilized to characterize exquisite phase formation of the composites. The temperature dependent dielectric properties was performed in a broad range from 100 Hz to 1 MHz and it exhibits a diffuse phase transition in high temperature region. The Non-Debye type dielectric relaxation with grain and grain boundary contribution of different activation energy was confirmed by Nyquist plot (Z′−Z′′) of impedance spectra. Broad dielectric relaxation plateau was observed in the low temperature and high frequency region and electronic hopping motion with interfacial polarization is the underlying mechanism of it, instead of dipolar relaxation and internal barrier effect. The real ac conductivity was fitted by well-known Almond-west equation and the temperature dependent frequency exponent (S) confirmed double overlapping large polaron tunneling model (OLPT) model of electrical conduction mechanism from room temperature (298 K) to 533 K. The ac activation energies varries from 0.39 eV to 0.21 eV with high frequency dispersion and variable range hoppping (VRH) model is introduced to correlate the dc conductivity.

Assessment of Contribution of Curie-Spin Mechanism in Proton Relaxation During Aggregation Process of Hemoglobin S

Previous works showed a significant increase in the rotational correlation time of the water bound to the hemoglobin S during the aggregation process under sickle cell disease. In this case, the contribution of “Curie-Spin” relaxation mechanism to proton relaxation may be expected. The Curie-Spin relaxation mechanism has been well described theoretically but only a few experimental evidences have been presented. Based on the reported correlation times, the contribution of the Curie-spin relaxation mechanism to proton relaxation times ( $${T}_{1}$$ and $${T}_{2}$$ ) has been estimated in comparison with the contribution of the dipole–dipole relaxation mechanism at the extreme stages of the aggregation process of the hemoglobin S. This contribution is about 25% and 50% in the spin–spin relaxation rates at the magnetic field of 1.5 T during the latent and ending stages of the aggregation process, respectively. At lower magnetic fields, this mechanism gives an insignificant contribution. The contribution to the spin–lattice relaxation is negligible even at 1.5 T. In particular, this relaxation mechanism should be taken into account when interpreting experiments related to MRI.

Effect of Gd on structural, dielectric and electrical transport properties of multiferroic ceramic composite BiFeO3–NaNbO3

The multiferroics composite of (1- x)(BiFe1-yGdyO3)– xNaNbO3 (BFGNNO) with x = 0.25, 0.45 and y = 0.10, 0.20 were prepared by a high-temperature solid-state reaction technique. Structural characterization was performed by X-ray diffraction which confirms the formation of the ceramic and the materials show rhombohedral structure at room temperature. Frequency and temperature dependence of dielectric constant (εr) and dielectric loss (tanδ) of samples were measured in wide range of frequency (100 Hz to 1 MHz) and temperature (25 °C to 450 °C) using an LCR meter. The analysis of the study shows that the εr and tanδ decreases with increasing frequency in the given range for all the samples which can be explained through the occurrence of dipole relaxation process. There is enhancement of dielectric constant observed with increasing the Gadolinium (Gd) concentration. The dielectric anomalies are observed in the studied sample at about 390 °C which found to be shifting towards higher temperature side on increasing the frequency. The frequency variation of ac conductivity shows that the compound obeys Jonscher's universal power law. The variation of ac conductivity with inverse temperature found to obey the Arrhenius equation and the materials show negative temperature coefficient of resistance (NTCR) behavior.

1H spin-lattice NMR relaxation in the presence of residual dipolar interactions – Dipolar relaxation enhancement

A model of spin-lattice relaxation for spin-1/2 nuclei in the presence of a residual dipole-dipole coupling has been presented. For slow dynamics the model predicts a bi-exponential relaxation at low frequencies, when the residual dipole-dipole interaction dominates the Zeeman coupling. Moreover, according to the model a frequency-specific relaxation enhancement, referred to as Dipolar Relaxation Enhancement (DRE) in analogy to the Quadrupole Relaxation Enhancement (QRE) is expected. The frequency position of the relaxation maximum is determined by the amplitude of the residual dipole-dipole interaction. Experimental examples of relaxation properties that might be attributed to the DRE are presented. The DRE effect has the potential to be exploited, in analogy to QRE, as a unique source of information about molecular dynamics and structure.

AC conductivity measurements of liquid-solid insulation of power transformers with high water content

• Electron tunneling takes place between neighboring potential wells, water nano-drops. • In materials there are two types of hopping conductivity. • Activation energy of relaxation times at growth stages in σ( f ) plots are similar. • Composition and structure nanoparticles, between which electrons tunnel, are similar. The paper investigated the influence of temperature on the frequency dependence of the conductivity of cellulose-ester insulation of power transformers containing nano-drops of water. It was observed that in the insulation containing nano-drops of water on the σ( f ) dependence two sections of conductivity increase occur. It was found that the state of the frequency dependence of conductivity is affected simultaneously by the temperature dependence of conductivity and the temperature dependence of dipole relaxation time. Activation energies for conductivity and relaxation times were determined, the values of which are the same for both stages of the conductivity increase. This means that the structure of water nanoparticles, between which electrons tunnel, is the same for both stages of σ( f ) growth. The occurrence of the two growth stages on the frequency dependence of conductivity is associated with differences in distances between adjacent nanoparticles and the associated relaxation times.

Investigation into the dynamic molecular and conductivity mechanisms of piezoelectric ceramics Pb[ZrxTi1−x]O3/epoxy piezocomposites

AbstractThroughout this work, an experimental and theoretical analysis of the molecular dynamics, correlated with the alternating current conductivity σac(ω, T),of unidirectional piezoelectric composites used as actuators and/or sensors in different systems was carried out. The 3D‐representation of the imaginary part M″(ω, T) of the electric modulus shows, apart from the presence of the classical secondary β and the primary α dipolar relaxation processes, the appearance of a new peak attributed to the Maxwell‐Wagner‐Sillars (MWS) interfacial polarization whose amplitude depends on the rate of reinforcement. In our case, since we are usually within the range of fragile materials, the stiffness of the 26% fiber content composite is about 4.5 times greater than that of 13.4% (via the fragility parameter D), shows a less pronounced curvature and the nature of the relaxation times is closer to the Arrhenius type. Due to the high dispersion of the conductivity with the frequency of applied electrical field in the range (1‐104 Hz), Jonscher's “universal power law” has been revised by adding a new term, which takes into account the displacement current density. The ac conductivity adjustment procedure, using the new obtained expression, turns out to be accurate and follows the experimental data reported in the low, high, and even intermediate frequency domains. This theoretical approach allowed us to determine the key parameters (∆ε, τmax,…) unique to each relaxation process, and to demonstrate the MWS interfacial polarization that is directly linked to the adhesion between the PZT fibers and the epoxy resin matrix.

Relaxation Time, Excess Relaxation Time and Dipole Moment of Binary Mixture of 2,3-Dichloroaniline and 2-Methoxyethanol using Frequency Domain Reflectometer

Dielectric constant (e') and dielectric loss (e) of 2,3-Dichloroaniline (2,3-DCA), 2-Methoxyethanol (2-ME) and binary mixtures of 2,3-DCA+2-ME in 1,4-dioxane solutions have been measured at microwave frequency 10.985 GHz at different temperatures 20 0 C, 30 0 C, 40 0 C and 50 0 C. Standing microwave techniques and Gopala Krishna’s single frequency concentration variation method have been used for above measurements. The measured values of e¢ and e¢¢ have been used to evaluate dipole moment (µ) and relaxation time (τ). The dielectric relaxation process of binary mixtures containing 70% mole fraction of 2,3-DCA have been calculated. It is found that the dielectric relaxation process can be treated as the rate process like the viscous flow process. Nonlinear variation of relaxation time with molar concentration of 2,3-DCA in the whole concentration range of the binary mixture indicates the existence of solute-solute and solute–solvent type of molecular association was predicted. Dipole moment (µ) of 2,3-DCA and 2-ME slightly non-linearly increases with rise in temperature. Excess inverse relaxation time (1/τ) e calculated at different temperatures are found to be positive. All parameters (e'), (e), (τ), (1/τ) e and (μ) are calculated and discussed to yield information on the dipole alignment and molecular rotation of the binary liquid mixtures. From all the derived dielectric parameters, molecular interactions are interpreted through hydrogen bonding. DOI: http://dx.doi.org/10.17807/orbital.v12i2.1368

Microwave dielectric relaxation spectroscopy of paracetamol and its aqueous solutions

The complex dielectric function ε∗(ω) = ε ′ (ω) – jε ″ (ω) is studied for aqueous solutions of Paracetamol (PCM) (at four different temperatures 293.15 K, 303.15 K, 313.15 K and 323.15 K) across the frequency range of 200 MHz to 30 GHz and of pure PCM in pellet form (at a constant temperature of 300.15 K) over the frequency ranging from 200 MHz to 20 GHz. Dielectric properties are measured using Anritsu Shockline Vector Network Analyser (VNA) Model No. MS46322A, SPEAG DAK – 1.2 (5–50 GHz) and DAK – 3.5 (200 MHz–20 GHz) probes. Obtained dielectric data are further analysed with Debye relaxation model in order to understand the dipolar relaxation behaviour of these solutions. From obtained dielectric data; other parameters like power reflected (Pr), power transmitted (Pt), penetration depth (dp) have also been determined at 2.45 GHz and analysed in view of its applicability for microwave dielectric heating in pharmaceuticals. Temperature dependence of the dipolar relaxation time is used to evaluate thermodynamical parameters: Gibbs free energy of activation (ΔFe), entropy of activation (ΔSe) and enthalpy of activation (ΔHe).

The Effect of the Cooling Process on the Crystalline Morphology and Dielectric Properties of Polythene.

In this study, LDPE samples were prepared by melt blending with different cooling processes, which were natural air cooling, rapid air cooling, water cooling and oil cooling, respectively. According to polarization microscope (PLM) and differential scanning calorimeter (DSC) tests of these four low-density polyethylene (LDPE) samples, the effect of different cooling processes on polythene crystalline morphology could be studied. According to conductivity, dielectric frequency spectra and space charge tests, the effect of crystalline morphology on dielectric macroscopic properties could be explored. The microstructure characteristic results indicated the cooling medium significantly affected polythene crystalline morphology. When the samples were produced with natural air cooling, the crystalline grain size was large. On the other hand, after rapid air cooling, water cooling and oil cooling processes, the samples’ crystalline grain dispersed uniformly, and the grain sizes were lower. The space charge testing results indicate the samples produced with water cooling and oil cooling processes restrained the electrode injection in the process of pressurization. During short-circuits, the rates of charge release of these two samples were fast, and the remaining space charges were fewer. The conductivity and dielectric frequency spectra testing results indicated the conductivities of samples produced with water cooling and oil cooling processes were both less than those of samples produced with a natural air cooling process. Besides, with increasing experimental frequency, the relative dielectric constants of all testing samples decreased. Among them, the relative dielectric constant of the LDPE sample with the natural air cooling process was the largest. However, the crystalline structures of samples produced with rapid air cooling and water cooling processes were close, which restrained the movement of polymer macromolecule chains. Thus, the dielectric constants were lower. Additionally, because of the influence of relaxation polarization and dipole polarization, the dielectric losses of LDPE with water cooling and oil cooling processes increased to varying degrees.

Cellular metabolism and colloids: Realistically linking physiology and biological physical chemistry

Important concepts from colloidal physical chemistry such as coacervation, phase transitions, emergent properties and ionic association, are currently emerging in the lexicon of cellular biology, prompted mostly by recent experimental observations of liquid phase coexistence in the cell cytosol. Nevertheless, from an historical point of view, the application of these concepts in cell biology is not new. They were key concepts into the so-called protoplasmic doctrine, an alternative (and largely forgotten) approach to cell physiology. The most complete theory originating from this line of thinking was the Association-Induction Hypothesis (AIH), introduced by Gilbert N. Ling in 1962. The AIH, which envisions living cells as complex dynamical colloidal systems, provides ample theory and experimental evidence to call into question the now dominant view of living cells as fluid-filled vesicles. This review attempts to present and discuss the usefulness of the AIH to understand a series of experimental observations from our laboratory from living suspensions of the yeast Saccharomyces cerevisiae exhibiting glycolytic oscillations. Particularly, the AIH helped us integrate, in a mechanistic sense, the basis of a strong temporal coupling observed between ATP and a series of cellular properties such as intracellular water dipolar relaxation, intracellular K+ concentration, among many others, where the colloidal physical chemistry of the cell interior plays a fundamental role.

Efficient affinity ranking of fluorinated ligands by 19F NMR: CSAR and FastCSAR.

Fluorine NMR has recently gained high popularity in drug discovery as it allows efficient and sensitive screening of large numbers of ligands. However, the positive hits found in screening must subsequently be ranked according to their affinity in order to prioritize them for follow-up chemistry. Unfortunately, the primary read-out from the screening experiments, namely the increased relaxation rate upon binding, is not proportional to the affinity of the ligand, as it is polluted by effects such as exchange broadening. Here we present the method CSAR (Chemical Shift-anisotropy-based Affinity Ranking) for reliable ranking of fluorinated ligands by NMR, without the need of isotope labeled protein, titrations or setting up a reporter format. Our strategy is to produce relaxation data that is directly proportional to the binding affinity. This is achieved by removing all other contributions to relaxation as follows: (i) exchange effects are efficiently suppressed by using high power spin lock pulses, (ii) dipolar relaxation effects are approximately subtracted by measuring at two different magnetic fields and (iii) differences in chemical shift anisotropy are normalized using calculated values. A similar ranking can be obtained with the simplified approach FastCSAR that relies on a measurement of a single relaxation experiment at high field (preferably > 600MHz). An affinity ranking obtained in this simple way will enable prioritizing ligands and thus improve the efficiency of fragment-based drug design.