Dissociation energy of the hydrogen molecule at 10−9^{-9} accuracy

The ionization energy of ortho-H$_2$ has been determined to be $E^\mathrm{o}_\mathrm{I}(\mathrm{H}_2)/(hc)=124\,357.238\,062(25)$ cm$^{-1}$ from measurements of the GK(1,1)--X(0,1) interval by Doppler-free two-photon spectroscopy using a narrow band 179-nm laser source and the ionization energy of the GK(1,1) state by continuous-wave near-infrared laser spectroscopy. $E^\mathrm{o}_\mathrm{I}$(H$_2$) was used to derive the dissociation energy of H$_2$, $D^{N=1}_{0}$(H$_2$), at $35\,999.582\,894(25)$ cm$^{-1}$ with a precision that is more than one order of magnitude better than all previous results. The new result challenges calculations of this quantity and represents a benchmark value for future relativistic and QED calculations of molecular energies.Comment: 6 pages, 5 figure

Determination of the Interval between the Ground States of Para- and Ortho- H2

ISSN:0031-9007ISSN:1079-711

Improved ionization and dissociation energies of the deuterium molecule

The ionization energy of D2 has been determined experimentally from measurements involving two-photon Doppler-free vacuum-ultraviolet pulsed laser excitation and near-infrared continuous-wave laser excitation to yield EI(D2)=124745.393739(26) cm-1. From this value, the dissociation energy of D2 is deduced to be D0(D2)=36748.362282(26) cm-1, representing a 25-fold improvement over previous values, and it was found to be in good agreement (at 1.6s) with recent ab initio calculations of the four-particle nonadiabatic relativistic energy and of quantum-electrodynamic corrections up to order ma6. This result constitutes a test of quantum electrodynamics in the molecular domain, while a perspective is opened to determine nuclear charge radii from molecules

The political economy of social assistance and minimum income benefits: a comparative analysis across 26 OECD countries

Social assistance benefit schemes are a peculiar type of welfare state program. As the electoral costs are relatively low, this program forms an obvious target for cost reduction in times of austerity. The aim of this study is to examine the determinants of the developments in social assistance benefits. We seek to make two contributions. First, this paper provides insight into the role of economic, political, and institutional determinants of the variation in social assistance benefits. Second, cross-national data on social expenditures and income replacement rates are available for several welfare state programs, but not for social assistance benefits. Presenting minimum income benefit replacement rates, this study analyzes the developments of social assistance benefits across 26 OECD countries over the past two decades. The analysis leads to the conclusion that budgetary pressure stemming from increased exposure to international trade and soaring levels of unemployment is associated with benefit cuts.The politics and administration of institutional chang