The rotational branching ratio in the photoelectron spectrum of H-2(+) has
been investigated using synchrotron radiation. At the photon energy hv = 23
eV, the S (Delta N = 2) branch has a considerably higher relative intensit
y than when excited with Her (lambda = 584 Angstrom, hv = 2 1.218 eV) or wi
th Ne I (lambda = 736 Angstrom, hv = 16.848 eV) radiation.