An alternative view of the coherent x-ray scattering factor with application to the hydrogen atom Am.The x-ray form factors for a bonded hydrogen in the hydrogen molecule have been calculated for a spherical approximation to the bonded atom. These factors may be better suited for the least-squares refinement of x-ray diffraction data from organic molecular crystals than those for the isolated hydrogen atom. It has been shown that within the spherical approximation for the bonded hydrogens in H 2 , a least-squares refinement of the atomic positions will result in a bond length (R. value) short of neutron diffraction or spectroscopic values. The spherical atoms are optimally positioned 0.07 A off each proton into the bond. A nonspherical density for the bonded hydrogen atom in the hydrogen molecule has also been defined and the corresponding complex scattering factors have been calculated. The electronic density for the hydrogen molecule in these calculations was based on a modified form of the Kolos-Roothaan wavefunction for H2• Scattering calculations were made tractable by expansion of a plane wave in spheroidal wavefunctions. 5 Compare K. Ruedenberg, Rev. Mod.

The interpretation of the absorption spectrum of a molecular crystal requires a knowledge of the strength of resonance force electrostatic interaction between molecules in the crystal as compared to an energy parameter characterizing the molecular vibrational level pattern. Depending on the relative magnitudes of these energy terms the spectrum reflects absorption by the crystal as a whole or by independent, though ori.ented m?lecul~s. These ~wo familia: cases are examined from both stationary-state and time-dependent pomts of VIew WIth the object of definmg the energy parameters. The resonance force interaction term is a theoretically derived quantity, the crystal electronic band width; the comparable vibrational energy term is shown to be the width of the total electronic band comprising all the vibronic transitions for an isolated molecule. Particular attention is given to the case in which these terms are nearly equal.

Sigma-bond electronic transitions in alkanes have been investigated both experimentally and theoretically. Vacuum ultraviolet spectra of a large number of alkanes have been recorded in the range 50 to 94 kK and absorption intensities as well as frequencies have been determined. The implications of vapor-phase conformational isomerism are discussed. A qualitative interpretation of the observed spectra has been developed using independent-systems theory in connection with a simple model in which excitations in only C–C bonds are considered. A reasonably good topological matching between theory and experiment is achieved. A quantitative theory in which C–H bond excitations are included has also been developed. With this theory parameters are derived from the spectra of methane and ethane which prove sufficient to describe the higher alkanes without recourse to ``fitting.'' The theoretical procedures used are outlined in the text and described in greater detail in an Appendix.

With relative humidity and temperature data from the National Oceanic and Atmospheric Administration, the average equilibrium moisture content for each month of the year was calculated for 262 locations in the United States and 122 locations outside the United States. As an aid for storage of kiln-dried lumber, a graph is presented for determining the reduction in equilibrium moisture content that results from heating air in an enclosed storage space above the temperature of the outside air.

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Topography of an electron cyclotron resonance plasma in the vacuum-ultraviolet spectral range Rev. Sci. Instrum. 73, 614 (2002);The electronic spectra of a number of divalent sulfur compounds in the vacuum ultraviolet are presented. A working criterion for the separation of non-Rydberg from Rydberg transitions is applied. The non-Rydberg transitions are then considered in the framework of NY theory, and assignments of the observed bands are made.E LECTRONIC spectra of compounds of divalent sulfur are here presented and discussed. Compounds studied include hydrogen sulfide, mercaptans, alkyl sulfides, and cyclic alkyl sulfides. The electronic transitions are (somewhat arbitrarily) separated into non-Rydberg and Rydberg transitions. In this paper the way the separation is obtained is first explained and illustrated, after which the non-Rydberg transitions in sulfides are generally identified and assigned. In the second, succeeding paper, the Rydberg transitions themselves are featured.

ContentsThis report reviews the basis for determining values for the density of wood as it depends on moisture content and specific gravity. The data are presented in several ways to meet the needs of a variety of users.

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