A zero ion kinetic energy spectrometer has been developed to study the production of near zero energy protons and deuterons from dissociative photoionization of H2 and D2. Both H+ and D+ spectra show four peaks on top of a continuum. The continuum was found to be in excellent agreement with the single center Coulomb calculation for the direct dissociation through the X 2Σ+g state of H+2. The observed structures were shown to originate from autoionization of the doubly excited Q1 1Σ+g(1), Q1 1Σ+u(1), Q1 1Σ+u(2), and Q2 1Σ+u(1) states, of which the Q1 1Σ+g(1) state is dipole forbidden.

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A method of determining the absolute beam current in the NBS electron storage ring SURF-I1 by electron counting is described. Recent improvements and the present implementation of the technique are discussed, along with the results of an intercomparison with the NBS spectral irradiance scale.

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Comparison of NIST's SURF-II primary irradiance standard and argon miniarc irradiance standard at 214 nm with an uncertainty of ~3% shows that at this wavelength these irradiance standards agree to within the uncertainties of 1.3 and 7%, respectively, assigned to them by NIST.

We have studied the polarization dependence of silicon photodiode responsivity as a function of wavelength, the angle of incidence, and the thickness of the silicon dioxide overlayer. The experimental results in the spectral region where there is no absorption in the silicon dioxide are explained well by a purely optical model. The responsivity dependence on polarization in the VUV is found to be smaller than that predicted and to be explainable by the presence of charge injection from the silicon dioxide layer.

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