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

Molecular preionization and predissociation

Some experimental and theoretical aspects of molecular preionization and predissociation are discussed with reference to the N2, H2 and N2O molecules. It is shown that molecular line shapes can have a more complicated form than generally anticipated