Chemistry Department Seminar

Date:
-
Location:
CP-114A/B
Speaker(s) / Presenter(s):
Dr. Charles M. Folden III

----------
This event was originally scheduled on February 20, 2015 but was rescheduled due to weather.

Dr. Charles M. Folden III will be presenting a seminar titled Prospects for the Discovery of the Next New Element and New Methods for Liquid-Phase Chemistry of Heavy and Superheavy Elements.

Abstract: Experiments in recent years have produced new spherical, shell-stabilized superheavy elements through Z = 118 in complete fusion neutron-evaporation reactions using projectiles of 48Ca reacting with actinide targets.  Unfortunately, projectiles with higher atomic numbers will be required for the discovery of heavier elements due to a lack of available target materials.  Recent experiments in my group at Texas A&M University have studied the effect of varying the projectile in so-called analog reactions, which also produce spherical, shell-stabilized nuclei, but with much larger cross sections.  The data show a substantial reduction in cross section when other projectiles are used compared to the reactions of 48Ca with the same targets.  A simple theoretical model has been developed which suggests that the probability of compound nucleus formation and the survival of compound nuclei are both negatively affected by the change from 48Ca.  In these reactions, significant collective effects decrease the probability that the excited nucleus will “survive” against fission and defy the assumption that strong shell-stabilization will increase the cross section.  These results suggest that the production of new spherical, shell-stabilized superheavy elements with Z > 118 could be very difficult.

Additionally, once a heavy element has been produced in a nuclear reaction, it can be collected for use in a chemical experiment.  A new “gas stopper” has been designed to reduce the kinetic energies of nuclear reaction products by a factor of 109, and has shown high efficiency in offline and online experiments.  Chemical systems capable of establishing intra-group trends among homolog elements in groups 4 and 13 have been developed using long-lived radioisotope tracers.  The separation of In and Tl using ionic liquids has been especially promising, as separation factors >105 have been achieved.
This talk will discuss the prospects for the discovery of new elements, and highlight recent developments in methods and instrumentation made by our group to study the liquid-phase chemical properties of heavy and superheavy elements.
 

Faculty Host: Dr. Steven Yates