Bruce Malcolm Monroe

Photopolymers for holography

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.

RATES OF REACTION OF SINGLET OXYGEN WITH SULFIDES

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.

PHOTOCHEMICAL ESTIMATION OF OXYGEN SOLUBILITY

Abstract— A photochemical technique for estimating the solubility of oxygen in a solvent has been developed and used to estimate the solubility of oxygen in chloroform. From a measurement of the change in rubrene concentration and rubrene fluorescence lifetime as a sealed rubrene solution is irradiated and from the fluorescence lifetime of rubrene in nitrogen, air and oxygen‐saturated solvent the oxygen solubility constant and rate constant for oxygen quenching of rubrene fluorescence can be measured. For chloroform these values are 9.8 mM/atm and 7.9 109M‐1 s‐1 respectively.

Photopolymers: Radiation-Curable Imaging Systems

Photopolymers can be viewed as a special type of radiation-curable system.1–6 In these systems, as with other radiation-curable systems, irradiation can be carried out in bulk to produce uniform physical property changes in the coating. However, by far the greatest utility for these materials has been derived from imagewise exposure, in which the physical property changes that occur on exposure are used for imaging purposes.

Rate constants for the reaction of singlet oxygen with derivatives of p-aminobenzoic acid

Summary p-Aminobenzoic acid and its derivatives are often topically applied to prevent damage to the skin by actinic radiation. It has recently been suggested that reaction of these compounds with photochemically generated singlet oxygen may contribute to the protective effect. The total rate constants for interaction (reaction plus quenching) of several p -aminobenzoic acid derivatives with singlet oxygen have been determined in chloroform. The low rate constants for interaction, ethyl p -aminobenzoate, 8 × 104M−1s−1 ethyl p-N, N-dimethylaminobenzoate, 5.5 × 106M−1s−1, and p-N,N-dimethylaminobenzaldehyde, 1.1 × 106M−1s−1, indicate that interaction with singlet oxygen is not an important mode of protection for these compounds.