Two resonances in the photodetachment spectrum of H, one just below the n = 3 threshold and the other just below the n =4 threshold, were observed decaying into H {n'=2)+e. The n =3 resonance shows a preference for the n'=2 channel when compared with total-detachment measurements. Fanoline-shape fits give central energies of 12.652+0.003 eV for H * (3) and 13.338+0.004 eV for H **(4). These values are in good agreement with current theoretical calculations. PACS number(s): 32.80.Fb, 31.50.+w, 32.80.Cy

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We have measured the hydrogen-deuterium isotope shift in the energy of the lowest 1 D e autodetaching resonance in the two-photon absorption spectrum of H Ϫ . The 1 D e resonance in negative deuterium lies 2.0 Ϯ0.5 meV, with a possible systematic error of 0.4 meV, above the corresponding resonance in negative hydrogen when measured with respect to the ion ground state. From the isotope shift, we obtain a mass polarization of 2.4Ϯ1.1 meV, with a possible sytematic error of 0.8 meV, for the 1 D e in H Ϫ under the assumption that the Fano shape parameters, q, for the two isotopes are the same. Recent theoretical calculations give the mass polarization for this resonance in H Ϫ as Ϫ0.1 meV. The generalized absolute cross section of two-photon absorption at the peak of the 1 D e is found to be (3.2 Ϫ1.2 ϩ1.8 )ϫ10 Ϫ49 cm 4 s. The measured asymmetry parameters ␤ 2 and ␤ 4 of the photodetachment process are 1.9Ϯ1.2 and 2.21Ϯ0.45, respectively, consistent with a pure D-wave distribution. Upper bounds on the second recursion of the lowest 1 S e resonance and three-photon excess photon detachment are 2.8ϫ10 Ϫ49 cm 4 s and 3.1ϫ10 Ϫ78 cm 6 s 2 , respectively.