Poverty Alleviation and the Degree of Centralisation in European Schemes of Social Assistance

Social Assistance; Classification; Centralisation; Poverty; Redistribution

DETERMINATION OF ROVIBRATIONAL INTERVALS IN H2+ WITH SUB-MHZ ACCURACY

H$_2^+$ is the simplest of all molecules and as such an important system for the development of molecular quantum mechanics. The rovibrational energy-level structure of this one-electron system can be calculated extremely precisely by quantum-chemical methods\footnote{V. I. Korobov, L. Hilico, and J.-Ph. Karr, Phys. Rev. A 89, 032511 (2014)}. By comparison with the results of precise spectroscopic measurements of rovibrational intervals, fundamental constants or particle properties, such as the proton-to-electron mass ratio or the proton size, can be determined\footnote{J.-Ph. Karr, L. Hilico, J. C. J. Koelemeij, and V. I. Korobov, Phys. Rev. A 94, 050501(R) (2016)}. Because the rotational and vibrational transitions of H$_2^+$ are electric-dipole forbidden, the experimental data on its energy-level structure are limited. We present the determination of spin-rovibrational intervals in H$_2^+$ from high-resolution measurements of the Rydberg spectrum of H$_2$ and Rydberg-series extrapolation using multichannel quantum defect theory\footnote{D. Sprecher, Ch. Jungen and F. Merkt, J. Chem. Phys. 140, 104303:1-18 (2014)}. Choosing suitable double-well valence states of H$_2$, characterized by long lifetimes and favorable Franck-Condon factors to different vibrational states in the ion, allows us to excite Rydberg states that converge on selected rovibrational levels of H$_2^+$. For the excitation of Rydberg states, a resonant three-photon excitation scheme was employed, using pulsed VUV and VIS laser sources to reach the intermediate valence state and a continuous-wave (cw) near-infrared laser source for the excitation to the Rydberg states. The valence state - Rydberg state intervals could be measured with a relative accuracy of 3E-10 using an optical frequency comb for the frequency calibration of the cw laser and minimizing systematic uncertainties\footnote{M. Beyer, N. H\"{o}lsch, J. A. Agner, J. Deiglmayr, H. Schmutz, and F. Merkt, Phys. Rev. A 97, 012501 (2018)}

IMPROVEMENT OF THE DISSOCIATION ENERGY OF THE HYDROGEN MOLECULE (PART TWO)

The dissociation energy $D_0$ of ortho H$_2$ is a benchmark quantity in quantum chemistry, with recent QED calculations now approaching accuracies achievable in simple atoms. In the light of recent discrepancies between experiment and theory [1], a combined effort (see also part one) has been undertaken to provide an improved experimental value for $D_0$. We report the transition frequency from the $GK~^1\Sigma_g^+~(v=1, N=1)$ state to the 56p~$(N=1, S=0,F=0-2)$ Rydberg state belonging to the series converging on the $X^+~^2\Sigma_g^+~(v^+=0,N^+=1)$ ground state of ortho H$_2^+$. A resonant three-photon excitation scheme was employed, using pulsed VUV and VIS laser sources to reach the intermediate GK state and a continuous-wave near-infrared (NIR) laser source for the transition to the Rydberg state. To reach the desired accuracy, the procedure involved [2]: (i) minimizing the Doppler width through the use of a doubly skimmed, supersonic molecular beam produced by a cryogenic pulsed valve, (ii) minimizing stray electric and magnetic fields, (iii) cancelling the first-order Doppler shift using two counterpropagating laser beams, (iv) calibrating the NIR-laser frequency using a frequency comb referenced to an atomic clock. The ionization energy of the intermediate $GK$ state was obtained by adding the binding energy of the Rydberg state determined previously by millimeter-wave spectroscopy and multichannel quantum-defect theory [3]. In combination with the $GK~^1\Sigma_g^+~(v=1,N=1) \leftarrow X~^1\Sigma_g^+~(v=0,N=1)$ transition frequency presented in part one, an order-of magnitude improvement for $D_0$ at the $10^{-9}$ level of accuracy has been achieved, while remaining consistent with the previously most precise determination [4]. \footnotesize{[1] M. Puchalski et al., Phys. Rev. A 95, 052506 (2017)}\quad\quad\quad\quad\quad \footnotesize{[2] M. Beyer et al., Phys. Rev. A 97, 012501 (2018)} \footnotesize{[3] D. Sprecher et al., J. Chem. Phys. 140, 104303:1-18 (2014)}\quad\quad \footnotesize{[4] J. Liu et al., J. Chem. Phys. 130 (17), 174306 (2009)

Switching the cofactor specificity of an imine reductase

Chiral amines have proven to be powerful building blocks for defining new pharmaceutical and agrochemicals due to their high density of structural information. In this light, the reduction of prochiral C=N double bonds is a well-established route in synthetic chemistry due to the easy accessibility of imines from their ketone precursors with the asymmetric addition of hydrogen or a hydride as the key stereo-differentiating step. Recently, we have witnessed remarkable advances in the enzyme-catalyzed asymmetric reduction of imines by NADPH-dependent imine reductases (IREDs).[1,2] Imine reductases were presented that catalyze the asymmetric reduction of various imines and the chemo- and stereoselective reductive amination as a useful method for the preparation of amines derived from aldehydes and ketones.[3,4] Please click Additional Files below to see the full abstract

DETERMINATION OF ROVIBRATIONAL INTERVALS IN H2+ WITH SUB-MHZ ACCURACY

H$_2^+$ is the simplest of all molecules and as such an important system for the development of molecular quantum mechanics. The rovibrational energy-level structure of this one-electron system can be calculated extremely precisely by quantum-chemical methods\footnote{V. I. Korobov, L. Hilico, and J.-Ph. Karr, Phys. Rev. A 89, 032511 (2014)}. By comparison with the results of precise spectroscopic measurements of rovibrational intervals, fundamental constants or particle properties, such as the proton-to-electron mass ratio or the proton size, can be determined\footnote{J.-Ph. Karr, L. Hilico, J. C. J. Koelemeij, and V. I. Korobov, Phys. Rev. A 94, 050501(R) (2016)}. Because the rotational and vibrational transitions of H$_2^+$ are electric-dipole forbidden, the experimental data on its energy-level structure are limited. We present the determination of spin-rovibrational intervals in H$_2^+$ from high-resolution measurements of the Rydberg spectrum of H$_2$ and Rydberg-series extrapolation using multichannel quantum defect theory\footnote{D. Sprecher, Ch. Jungen and F. Merkt, J. Chem. Phys. 140, 104303:1-18 (2014)}. Choosing suitable double-well valence states of H$_2$, characterized by long lifetimes and favorable Franck-Condon factors to different vibrational states in the ion, allows us to excite Rydberg states that converge on selected rovibrational levels of H$_2^+$. For the excitation of Rydberg states, a resonant three-photon excitation scheme was employed, using pulsed VUV and VIS laser sources to reach the intermediate valence state and a continuous-wave (cw) near-infrared laser source for the excitation to the Rydberg states. The valence state - Rydberg state intervals could be measured with a relative accuracy of 3E-10 using an optical frequency comb for the frequency calibration of the cw laser and minimizing systematic uncertainties\footnote{M. Beyer, N. H\"{o}lsch, J. A. Agner, J. Deiglmayr, H. Schmutz, and F. Merkt, Phys. Rev. A 97, 012501 (2018)}

IMPROVEMENT OF THE DISSOCIATION ENERGY OF THE HYDROGEN MOLECULE (PART TWO)

The dissociation energy $D_0$ of ortho H$_2$ is a benchmark quantity in quantum chemistry, with recent QED calculations now approaching accuracies achievable in simple atoms. In the light of recent discrepancies between experiment and theory [1], a combined effort (see also part one) has been undertaken to provide an improved experimental value for $D_0$. We report the transition frequency from the $GK~^1\Sigma_g^+~(v=1, N=1)$ state to the 56p~$(N=1, S=0,F=0-2)$ Rydberg state belonging to the series converging on the $X^+~^2\Sigma_g^+~(v^+=0,N^+=1)$ ground state of ortho H$_2^+$. A resonant three-photon excitation scheme was employed, using pulsed VUV and VIS laser sources to reach the intermediate GK state and a continuous-wave near-infrared (NIR) laser source for the transition to the Rydberg state. To reach the desired accuracy, the procedure involved [2]: (i) minimizing the Doppler width through the use of a doubly skimmed, supersonic molecular beam produced by a cryogenic pulsed valve, (ii) minimizing stray electric and magnetic fields, (iii) cancelling the first-order Doppler shift using two counterpropagating laser beams, (iv) calibrating the NIR-laser frequency using a frequency comb referenced to an atomic clock. The ionization energy of the intermediate $GK$ state was obtained by adding the binding energy of the Rydberg state determined previously by millimeter-wave spectroscopy and multichannel quantum-defect theory [3]. In combination with the $GK~^1\Sigma_g^+~(v=1,N=1) \leftarrow X~^1\Sigma_g^+~(v=0,N=1)$ transition frequency presented in part one, an order-of magnitude improvement for $D_0$ at the $10^{-9}$ level of accuracy has been achieved, while remaining consistent with the previously most precise determination [4]. \footnotesize{[1] M. Puchalski et al., Phys. Rev. A 95, 052506 (2017)}\quad\quad\quad\quad\quad \footnotesize{[2] M. Beyer et al., Phys. Rev. A 97, 012501 (2018)} \footnotesize{[3] D. Sprecher et al., J. Chem. Phys. 140, 104303:1-18 (2014)}\quad\quad \footnotesize{[4] J. Liu et al., J. Chem. Phys. 130 (17), 174306 (2009)