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We present "snapshot" observations with the NearInfrared Camera and MultiObject Spectrometer (NICMOS) on board the Hubble Space Telescope (HST) of 94 nearby galaxies from the Revised Shapley Ames Catalog. Images with 0.2 ′′ resolution were obtained in two filters, a broad-band continuum filter (F160W, roughly equivalent to the H-band) and a narrow band filter centered on the Pa α line (F187N or F190N, depending on the galaxy redshift) with the 51 ′′ ×51 ′′ field of view of the NICMOS camera 3. A firstorder continuum subtraction is performed, and the resulting line maps and integrated Pa α line fluxes are presented. A statistical analysis indicates that the average Pa α surface brightness in the central regions is highest in early-type (Sa-Sb) spirals.

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Photosensitive films composed of dye, initiator, acrylic monomers, and polymeric film-forming binder, and their use in recording volume phase transmission and reflection holograms are described. Systematic variation of monomer-binder combinations reveals that the maximum attainable index modulation (hologram efficiency) increases with increasing difference between the refractive indices of monomer and binder. Addition of plasticizer is also useful for increasing index modulation. Thermal and wet chemical processing methods for altering hologram properties are described.

Abstract—Reaction rate constants for the reaction of singlet oxygen with a series of 24 sulfides in chloroform have been measured by inhibition of the self‐sensitized photooxidation of rubrene. The reaction rate constant is sensitive to steric effects, decreasing as the carbons α‐ to sulfur become more highly substituted. Addition of a methyl group to each of the carbons α‐ to sulfur decreases the rate constant by about a factor of 10. From a series of p‐ and m‐substituted thioanisoles, a ρ of ‐1.67 ± 0.09 was found. A much better correlation was found with σ than with σ+ indicating there is no resonance interaction with the reaction center. Typical rate constants are: di‐n‐butyl sulfide, 2.3 × 107M‐1 s‐1; CBZ‐L‐methionine methyl ester, 1.4 × 107; di‐s‐butyl sulfide, 1.8 × 106; di‐t‐butyl sulfide, 1.3 × 105; and thioanisole, 2.3 × 106.