Patterns with high rhythmicity levels in multicomponent Liesegang systems.
Liesegang banding is the display of rhythmic strata of precipitate as co-precipitate ions interdiffuse in a gel medium. Complex periodic patterns as well as aperiodic structures could emerge, notably in systems where more than one salt is precipitated. The use of three cations (Co2+) Ni2+, and Mg2+) in the banded precipitation of their hydroxides resulted in an unusual pattern with a consistently increasing rhythmicity. A periodic structure marked by the succession of band multiplets with increasing number of bands (from singlets to doublets to triplets to quadruplets, consistently) was observed. Such rhythmic patterns are obtained as the initial Mg2+ concentration ([Mg2+]0), chosen as a control parameter, increases through a critical value. At high [Mg2+]0, the trend breaks after a long time elapses. Two types of bifurcation are therefore experienced by such a system: concentration bifurcation and diffusive (time/space) bifurcation. The dynamics is elucidated on the basis of an analysis of the bands in certain groups, and gel regions between these groups, as well as between group blocs (here, a bloc denotes a succession of multiplet groups, with repetitively the same number of bands). Finally, similarities between our system and naturally occurring rhythmic patterns are emphasized and discussed.
Msharrafieh
Maysam
M
Department of Chemistry, American University of Beirut, PO Box 11-0236, Riad El Solh 1107 2020, Beirut, Lebanon.
Sultan
Rabih
R
D002412:Cations / Q000032:analysis; D055598:Chemical Phenomena; D011232:Chemical Precipitation; D002627:Chemistry, Physical; D003035:Cobalt / Q000032:analysis; D004573:Electrolytes / Q000737:chemistry; D005782:Gels; D008274:Magnesium / Q000032:analysis; D008956:Models, Chemical; D009532:Nickel / Q000032:analysis; D010507:Periodicity
D002412:Cations; D004573:Electrolytes; D005782:Gels; D003035:Cobalt; D009532:Nickel; D008274:Magnesium