Enhancement of metallic silver monomer evaporation by the adhesion of polar molecules to silver nanocluster ions. Technical report

Technical Report · Wed Sep 21 04:00:00 UTC 1994

OSTI ID:7022641

Fagerquist, C; Sensharma, D K; Rubio, A; Cohen, M L; El-Sayed, M A

The authors have compared the metallic evaporation channels from metastable Ag(X=5,7,11)(AgI)(Y=1-4)(+) clusters in the 1st FFR of a double focussing mass spectrometer with that of the corresponding pure metallic clusters, Ag(X=5,7,11)(+). It is found that the presence of the polar AgI molecules increases the rate of silver monomer evaporation relative to that of silver dimer evaporation. Using thermodynamic expressions for the heat of evaporation of the different evaporation processes and assuming the absence of reverse activation energies, an expression for the difference between the activation energy of silver monomer and dimer evaporation is derived. It is shown that dipole/induced-dipole forces resulting from the presence of AgI polar molecules lead to an enhancement of silver monomer evaporation if the polarizability of the pure metallic cluster ions increases with the number of Jellium electrons. The authors theoretical calculations of the static polarizabilities of (Ag(x))(+) using time dependent density functional theory within the local density approximation, shows a smooth increase in the polarizabilities with the number of the Jellium electrons in these clusters. Finally, the authors observe that the enhancement of Ag monomer evaporation per AgI added is smaller for clusters with even number of AgI molecules than with odd numbers. This was proposed to result from the contribution of configurations with dipole 'pairing' of the AgI molecules in clusters with even number of AgI molecules. Dipole pairing would decrease the average dipole/induced-dipole interaction between the AgI molecules and the metallic part of these 'mixed' clusters.

• Research Organization: California Univ., Los Angeles, CA (United States). Dept. of Chemistry
• OSTI ID: 7022641
• Report Number(s): AD-A-284936/2/XAB; TR--78; CNN: N00014-89-J-1350
• Country of Publication: United States
• Language: English

Related Subjects

664500* -- Special Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ATOMIC CLUSTERS
DIMERS
DOCUMENT TYPES
ELEMENTS
EVAPORATION
HALIDES
HALOGEN COMPOUNDS
IODIDES
IODINE COMPOUNDS
METALS
MONOMERS
PHASE TRANSFORMATIONS
PROGRESS REPORT
SILVER
SILVER COMPOUNDS
SILVER IODIDES
THERMODYNAMICS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS