UV/vis spectra of hydrated and activated Ag+ x Na+ 12-x A, Ag+ x Ca2+ 6-0.5x A, and Ag+ 9.5ZK-4 materials were studied. Any absorption band or color observed in silver zeolite A materials is due to the presence of silver ions. The marked site preference of ions in Ag+ x Ca2+ 6-0.5x A was found to offer the unique possibility of investigating different coordination sites of Ag+ ions in zeolite A. Observations we made lead to the result that Ag+ coordinated to 6- and 8-ring oxygens gives rise to electronic transitions in the near-UV region. Only Ag+ coordinated to 4-ring oxygens leads to the 22 000 cm-1 absorption responsible for the typical deep yellow color. The red color which is caused by a strong absorption band at 19 000 cm-1 is observed if a 4-ring coordinated Ag+ has a second Ag+ as a neighbor. We assume that the second Ag+ is at a 6-ring site. Yellow and red colored materials turn colorless again when exposed to humidity. The reversibility is complete for the yellow samples while a broad but weak absorption in the near-UV remains after rehydration of the red samples. Molecular orbital calculations were carried out on a unit structure cell consisting of 1296 atoms. The occupied frontier orbital region consists mainly of two bunches of levels:  the HOMO region which spreads from about −11 to − 12.6 eV and the next lower lying levels below −13.6 eV. The HOMO region consists of oxygen lone pairs O(n). We find that 6-ring coordinated Ag+ gives rise to near-UV electronic transitions and 4-ring coordinated Ag+ causes a band in the visible. These transitions can be interpreted as charge transfer from zeolite oxygen lone pairs to Ag+. We therefore denote them as Ag+(5s) ← O(n) LMCT.

visible and UV spectra visible and UV spectra (solids and liquids) D 6520 -018Quantum-Sized Silver Sulfide Clusters in Zeolite A. -The reaction of H 2 S with activated Ag + -loaded zeolite A leads to silver sulfide zeolite A composites (AgxS x/2 Na 12−x HxSi 12 Al 12 O 48 ·nH 2 O). The optical absorption and emission spectra of samples with different loading densities of Ag 2 S strongly suggest the presence of small Ag 2 S clusters. The effect of the variation of the Ag 2 S content on the emission spectra is remarkable. The luminescence is blue-green for samples with low Ag 2 S content, yellow or orange at medium Ag

No abstract

Not the Ag clusters, but rather the O atoms are responsible for the yellow color of silver-containing zeolite A. The reason for this has remained unclear since 1962. It is now shown that a charge-transfer transition from the lattice oxygen atoms to the empty 5s orbital of the silver ions (shown schematically on the right) is responsible for the yellow coloring.

For digital video subscription platforms, creating and managing content portfolios are critical to acquire new customers, retain existing customers, leverage cross-sales, and generate advertising revenues. We treat content portfolios as a form of pure bundling which may vary in composition and attractiveness over time. Therefore, evaluating the value contribution of each content piece is essential to manage a platform’s portfolio efficiently and to understand how a specific content piece contributes to the bundle’s attractiveness. In this article, we develop an ROI content valuation framework for a digital film subscription platform. This framework describes how a single piece of content diffuses through consumers’ journeys and influences subscription fees through acquisition and retention as well as revenues from cross-sales and advertising. This conceptual approach allows us to address the heterogeneity across content and platform contingencies such as exclusive availability and platform specifics, and link them to revenue streams. Building on this framework, we offer avenues for future research and provide potential lead performance indicators together with their operationalization, enabling all parties involved in the production, marketing, distribution, and sales of content to determine the platform-specific value of a content piece.