SOME CHEMICAL PROPERTIES OF EXCITED STATES.
Abstract
Aqueous solutions of acriflavine fail to obey Beer's Law. The spectroscopic data are explained in terms of a monomer-dimer equilibrium for the dye, with a dimer dissociation constant 0.001 M at 25C. The dimer may be stabilized by hydrophobic bonding and is of the non-parallel type. The decay of phosphorescence of adsorbates of acriflavine on silica gel is the sum of two first-order processes. The similarity of spectroscopic features of the adsorbates and the solutions suggests that dimers and monomers are the two components in the adsorbate. Oxygen quenches the phosphorescence of the adsorbates by forming a pre-illumination complex with the dye. The actual lifetime of phosphorescence of each dye component is invariant from 0 to 90% quenching by oxygen. At high populations of dye triplets, oxygen stimulates a blueshifted luminescence and is itself consumed. An inert gas can inhibit the enhancement of luminescence and the consumption of oxygen if the inert gas, like N2O, CH4, and CO2, has a vibrational spacing close to those occurring in O2. O2 is assumed to acquire vibrational energy in the initial quenching process and to use this as an energy of activation for subsequent dark reactions which are chemiluminescent. The initial enhanced quenching on the addition of mixtures of O2 with CO2 or N2O was shown to be a sensitive indicator of the adsorption of these gases on the surface of silica gel. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 20, 1964
- Accession Number
- AD0610640
Entities
People
- J. L. Rosenberg
Organizations
- University of Pittsburgh