Polarizability Correction Research Articles

Nuclear polarizability effects in He+3 hyperfine splitting

The nuclear polarizability effects in hyperfine splitting of light atomic systems are not well known. The only system for which they were previously calculated is the hydrogen atom, where these effects were shown to contribute about 5\% of the total nuclear correction. One generally expects the polarizability effects to become more pronounced for composite nuclei. In the present work we determine the nuclear polarizability correction to the hyperfine splitting in He$^+$ by comparing the effective Zemach radius deduced from the experimental hyperfine splitting with the Zemach radius obtained from the electron scattering. We obtain a surprising result that the nuclear polarizability of the helion yields just 3\% of the total nuclear correction, which is smaller than for the proton.

Bayesian analysis of nuclear polarizability corrections to the Lamb shift of muonic H-atoms and He-ions

The extraction of nuclear charge radii from spectroscopy experiments in muonic atoms is currently limited by the large uncertainties associated with the theoretical evaluation of the nuclear polarizability effects. To facilitate calculations, these polarizability corrections are conventionally expressed as an expansion in a dimensionless parameter η, which has been argued in previous literature to hold an approximate value of 0.33 in light-nuclear systems. In this work, we check this claim by doing a Bayesian analysis of the nuclear-polarizability corrections to the Lamb shift in μ 2H and μ 3H atoms and in μ 3He+ and μ 4He+ ions at various orders in the η-expansion. Our analysis supports the claim that η ≪ 1 in these systems and finds truncation uncertainties that are similar to the previous estimate, the only exception being the truncation uncertainties in the μ 3He+ ion, which are found to be larger.

Use of polarizability to correct the group-contributed normal boiling points of perfluorinated compounds

Perfluorinated compounds (PFCs) with cyclic structure or carbonyl groups that are easy to degrade are attractive as promising ozone depleting substance (ODS) substitutes for future use including fire suppression. To obtain their normal boiling points as accurate as possible but with minimal effort, a very simple group contribution method corrected by polarizability was proposed in this study. From the regression analysis of isomeric alkanes, polarizability correction was found to be viable to distinguish among isomers and therefore improve the accuracy of boiling point estimation. Based on this, a similar strategy was then adopted for PFCs. The root-mean-square error (RMSE) of their boiling point estimates was reduced from 8.41 K to 3.86 K after polarizability correction. Besides, to further illustrate the reliability of the proposed method, boiling point prediction of three other homologous PFCs was also conducted. The corrected results were closer to the reported ones, indicative of sufficient accuracy and acceptable deviation. Therefore, the proposed method can be considered as an effective way for predicting the boiling points of PFCs, and will provide guidance for the selection, optimization and application of environmentally friendly PFCs candidates.

Two-photon exchange on the neutron and the hyperfine splitting

We calculate the contribution from the two-photon exchange on the neutron to the hyperfine splitting of S energy levels. We update the value of the neutron Zemach radius, estimate total recoil and polarizability corrections. The resulting two-photon exchange in electronic atoms exceeds by an order of magnitude the leading Zemach term and has different sign both in electronic and muonic hydrogen.

Dispersion Theory in Electromagnetic Interactions

We review various applications of dispersion relations (DRs) to the electromagnetic structure of hadrons. We discuss the way DRs allow one to extract information about hadron structure constants by connecting information from complementary scattering processes. We consider the real and virtual Compton scattering processes off the proton, and summarize recent advances in the DR analysis of experimental data to extract the proton polarizabilities, in comparison with alternative studies based on chiral effective field theories. We discuss a multipole analysis of real Compton scattering data, along with a DR fit of the energy-dependent dynamical polarizabilities. Furthermore, we review new sum rules for the double-virtual Compton scattering process off the proton, which allow for model-independent relations between polarizabilities in real and virtual Compton scattering, and moments of nucleon structure functions. Information on double-virtual Compton scattering is used to predict and constrain the polarizability corrections to muonic hydrogen spectroscopy.

Anion halogen bonding effect on solvatochromism and excited state dynamics of hemicyanine dye in chlorinated solvents

Anion halogen bonding effect on solvatochromism and excited state dynamics of donor-π-acceptor hemicyanine dye 1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)pyridinium perchlorate (LDS-698) in chlorinated solvents were explored using steady state absorption, fluorescence and femtosecond time-resolved fluorescence studies. The anomalous bathochromic shift in the intramolecular charge transfer (ICT) absorption maximum of LDS-698 in chlorinated solvents is due to the specific halogen bonding interaction between the perchlorate anion and chlorinated solvents, which affect the ion-pair interaction and ground state energy. The presence of halogen bonding decreases the ion-pair interaction and account for the polarizability correction term in the in the Kamlet-Abboud-Taft solvatochromic analysis. The ultrafast time-resolved fluorescence studies confirm the radiative relaxation from locally-excited (LE), ICT and twisted intramolecular charge transfer (TICT) state. The excitation wavelength dependent decay of LDS-698 indicates the direct population of ICT state in chlorinated solvents. In cationic polymethine dyes, the symmetry breaking induced by the ion-pair effect is reversed by the halogen bonding interaction of the anion with chlorinated solvents.

Two-photon exchange correction to the hyperfine splitting in muonic hydrogen

We reevaluate the Zemach, recoil and polarizability corrections to the hyperfine splitting in muonic hydrogen expressing them through the low-energy proton structure constants and obtain the precise values of the Zemach radius and two-photon exchange (TPE) contribution. The uncertainty of TPE correction to S energy levels in muonic hydrogen of 105 ppm exceeds the ppm accuracy level of the forthcoming 1S hyperfine splitting measurements at PSI, J-PARC and RIKEN-RAL.

Hadronic deuteron polarizability contribution to the Lamb shift in muonic deuterium

Hadronic deuteron polarizability correction to the Lamb shift of muonic deuterium is calculated on the basis of unitary isobar model and modern experimental data on the structure functions of deep inelastic lepton–deuteron scattering and their parametrizations in the resonance and nonresonance regions.

Muonic-hydrogen Lamb shift: Dispersing the nucleon-excitation uncertainty with a finite-energy sum rule

We assess the two-photon exchange contribution to the Lamb shift in muonic hydrogen with forward dispersion relations. The subtraction constant $\bar T(0,Q^2)$ that is necessary for a dispersive evaluation of the forward doubly-virtual Compton amplitude, through a finite energy sum rule, is related to the fixed J=0 pole generalized to the case of virtual photons. We evaluated this sum rule using excellent virtual photoabsorption data that are available. We find that the "proton polarizability correction" to the Lamb shift in muonic hydrogen is $-(40\pm5)\mu$eV. We conclude that nucleon structure-dependent uncertainty by itself is unlikely to resolve the large (300$\mu$eV) discrepancy between direct measurement of the Lamb shift in $\mu H$ and expectations based on conventional Hydrogen measurements.

Forward virtual Compton scattering and the Lamb shift in chiral perturbation theory

We compute the spin-independent structure functions of the forward virtual-photon Compton tensor of the proton at one loop using heavy baryon chiral perturbation theory and dispersion relations. We study the relation between both approaches. We use these results to generalize some sum rules to virtual photon transfer momentum and relate them with sum rules in deep inelastic scattering. We then compute the leading chiral term of the polarizability correction to the Lamb shift of hydrogen and muonic hydrogen. We obtain $\ensuremath{-}87.05/{n}^{3}\mathrm{Hz}$ and $\ensuremath{-}0.148/{n}^{3}\mathrm{meV}$ for the correction to the hydrogen and muonic hydrogen Lamb shift, respectively.

An intramolecular induction correction model of the molecular dipole moment

A model for intramolecular polarization is presented. It is used to describe the changes in the molecular charge distribution occurring as a response to changes of dihedral angles in the molecule. The model is based on a multicenter multipole distribution of the molecular charge distribution. The electric field from this charge distribution induce dipole moments in the same molecule. The model contains atom type parameters to describe the damping of the electric field. A total of four atom types are used. The parameters are fitted to a calibration set with various functional groups, and tested against a validation set. The error obtained for the calibration set is reduced by 92% and by 88% for the validation set, if compared to an accurate state-of-the-art force field. It is shown that rotating the non-polarizable multicenter multipole distribution for the equilibrium geometry gives too large dipole moments for dihedral angles deviating from the equilibrium geometry. This will lead to too large long-range attractions in simulations. This problem is overcome by using the dipole polarizability correction suggested here, which gives dipole moments very close to the Hartree-Fock dipole moments obtained from reference calculations.

Nuclear vector polarizability correction to hyperfine splitting

The interaction of orbital electrons with the charge and magnetic moment of the nucleus polarizes it, and the detailed description requires a careful treatment of the nuclear vector polarizability. We present a complete and closed-form expression for the resulting contribution to hyperfine splitting in light atomic systems.

Nuclear polarizability of helium isotopes in atomic transitions

We estimate the nuclear polarizability correction to atomic transition frequencies in various helium isotopes. This effect is non-negligible for high precision tests of quantum electrodynamics or accurate determination of the nuclear charge radius from spectroscopic measurements in helium atoms and ions. In particular, it amounts to $28(3)$ kHz for 1S-2S transition in 4He+.

New evaluation of proton structure corrections to hydrogen hyperfine splitting

We consider the proton structure corrections to the hydrogen ground-state hyperfine structure, focusing on a state-of-the-art evaluation of the inelastic nucleon corrections — the polarizability corrections — using analytic fits to the most recent data. We find a value for the fractional correction Δpol of 1.3 ± 0.3 ppm. This is 1–2 ppm smaller than the value of Δpol one would deduce using hyperfine-splitting data and elastic proton structure corrections obtained from modern form factor fits. In addition, we discuss the derivations of the relevant formulas, paying attention to lepton mass effects and to questions surrounding the use of unsubtracted dispersion relations. PACS Nos.: 31.30.Gs, 32.10.Fn, 14.20.Dh, 13.40.Gp

Isotope Shift of the3 S1/22−2 S1/22Transition in Lithium and the Nuclear Polarizability

High precision calculation of the isotope shift of the 3(2)S(1/2)-2(2)S(1/2) transition in lithium is presented. The wave function and matrix elements of relativistic operators are obtained by using recursion relations. Apart from the relativistic contribution, we obtain the nuclear polarizability correction for 11Li. The resulting difference of the squared charge radii 11Li-7Li based on the measurements of Sánchez et al. [Phys. Rev. Lett. 96, 033002 (2006)10.1103/PhysRevLett.96.033002] is deltar(ch)(2)=0.157(81) fm(2), which significantly differs from the previous evaluation.

Effects of polarizability and hyperpolarizability on molecular spatial alignment in intense light fields

Considering the influences of polarizability and hyperpolarizability on molecular spatial alignment, we newly deduce the classical equation of molecular motion for the internuclear distance r and for the angle θ between molecular axis and laser polarization direction in intense light fields. Numerical simulations of molecular dynamic alignment are performed and discussed at intensities of 10 15–10 17 W/cm 2 and pulse durations of 100 fs and shorter than 100 fs. In our calculation, N 2 and Cl 2 molecules are selected as sample because they can represent the light molecule and heavy molecule, respectively. Our computational results show that the contributions of the molecular polarizability and hyperpolarizability to the degree of dynamic alignment all become strong when the laser intensity increases and the pulse duration narrows. And the role of hyperpolarizability on molecular dynamic alignment becomes comparable to that of linear polarizability term, even exceeds it in the conditions of high laser intensity and short pulse length. The characteristics of molecular angular distribution with only considering the effect of polarizability, second hyperpolarizability, and higher-order correction term of the hyperpolarizability, respectively, are very different. Their contributions to molecular dynamic alignment are systematically calculated and discussed in different laser intensities and pulse durations.

Experimental Constraints on Polarizability Corrections to Hydrogen Hyperfine Structure

We present a state-of-the-art evaluation of the polarizability corrections--the inelastic nucleon corrections--to the hydrogen ground-state hyperfine splitting using analytic fits to the most recent data. We find a value Delta(pol)=1.3+/-0.3 ppm. This is 1-2 ppm smaller than the value of Delta(pol) deduced using hyperfine splitting data and elastic nucleon corrections obtained from modern form factor fits.

Proton-polarizability effect in the Lamb shift for the hydrogen atom

The proton polarizability correction to the Lamb shift of electronic and muonic hydrogen is calculated on the basis of isobar model and experimental data on the structure functions of deep inelastic lepton-nucleon scattering. The contributions of the Born terms, vector-meson exchanges and nucleon resonances are taken into account in the construction of the photoabsorption cross sections for transversely and longitudinally polarized virtual photons sigma_{T,L}.

Effect of polymer concentration on partitioning and molecular recognition in plasticized poly(vinyl chloride).

Mixtures of poly(vinyl chloride) (PVC) with plasticizers have been used in ion-selective electrodes for many years. The same material has proven useful in solid-phase microextraction (SPME), both with and without artificial receptors. We hypothesized that by changing the polymer concentration in plasticized PVC membranes containing artificial receptor from the standard 33 wt %, the selectivity of the extraction of barbiturates over similar molecules could be improved. Partition coefficients and receptor-substrate formation constants of a target species, phenobarbital, in membranes with various polymer concentrations were determined. Diffusion coefficients of the solute phenobarbital in receptor-free membranes were also determined. Kamlet-Taft solvatochromic properties beta and pi* were measured for the PVC/dioctyl sebacate materials. Cohesive energy densities were calculated for the same materials. Partition coefficients for phenobarbital (from aqueous solution to membrane) decrease as [PVC] increases, while the formation constants for the complex of the solute with its receptor increase. Diffusion coefficients decrease as the polymer concentration increases as well. The increase in polymer concentration brings about a decrease in hydrogen-bonding basicity and an increase in dipolarity and cohesive energy density. The values of the solvatochromic parameters determined at various compositions are highly correlated; thus, it is impossible to calculate how much each factor contributes to the changes associated with partition and complex formation. The solvatochromic "polarizability correction factor" has been determined to be 0 for PVC. In SPME experiments at 30%, 40%, and 50% (w/w) PVC, as polymer concentration increases, selectivity for barbiturate extraction over other cyclic imides becomes better in the presence of barbiturate receptor and worse without receptor.

Use of Principal Component Analysis To Study the Importance of Solute “Polarizability Corrections” in Linear Solvation Energy Relationships

Gas chromatography retention data for 52 solutes on 7 stationary phases were examined by principal component analysis. Without relying on a priori knowledge of solvation parameters and regression analysis, we are able to study the applicability of Kamlet−Taft linear solvation energy relationships and provide independent insight into the most appropriate models. The abstract factors calculated by principal component analysis are correlated with known solute parameters. We compare regression equations, focusing particularly on the need for some type of “polarizability correction factor”, such as Abraham's R2 or Kamlet's δ2. The results show that some type of “polarizability correction” is required and that the continuous R2 parameter is more applicable than δ2.