Studies of Silver Bromide Clusters Isotopic Properties and Their Applications

The quantum size effect (QSE) studies of metallic and semiconductor nanoparticles have received considerable attention for their applications in superconductivity, visible light emission, quantum dot devices and industrial catalysts. The QSE properties of semiconductor AgBr nanoparticles have been thoroughly characterized for cluster larger than three nanometers in diameter, the QSE studies of clusters in the quantum size regime less than 3nm have been historically difficult to describe owing to weak optical absorption and challenge in keep cluster in small size range against self aggregation. Such difficulties have precluded probing the properties of these small clusters in many natural and engineered processes. Our previous investigation of silver bromide ionic clusters that prepared via the electroporation of vesicles using direct laser desorption -- time of flight -- mass spectrometry (DLD-TOF-MS) had successfully revealed relation ship between cluster structure and the UV absorption band shift. The turn-around point had been experimentally identified to be $ (Ag_3Br_2)^+ $, which is close to the theoretical prediction. Despite those successes, there a lot of questions not be answered. These unanswered questions include why DLD-TOF-MS spectra show an unsymmetrical cluster finger peaks? why the large clusters have much lower DLD-TOF-MS spectra intensity? Why the cluster UV absorption have such wide band and it takes so long time to observe the band shift? In this paper, we reexamine our previous theoretical work and systematically answer the above questions with symmetry and probability principles in molecular cluster growth range. We also discussed the isotopic properties of silver bromide clusters and their possible applications on the dark matter detection based on recent findings that isotopic atoms can decay while interact with dark matters.