Intermitentna haotična stanja u oksihalogenidnim oscilatornim reakcijama

Abstract

Oscilatorna dinamička stanja su veoma česta u prirodim procesima i stoga važna za postojanje živog sveta. Složeni prirodni sistemi poseduju veliki broj vrsta koje međusobno interaguju na različite načine i kao takvi su veoma komplikovani, ili gotovo nemogući, za detaljna eksperimentalna istraživanja, pa je potrebno da se osnovni fenomeni ispitaju u jednostavnijim hemijskim oscilatorima. U ove jednostavnije hemijske oscilatore spadaju oksihalogenidni oscilatori, od kojih su najpoznatiji Bray-Liebhafsky i Briggs-Rauscher predmet ove teze. U uzanom delu oscilatorne oblasti mogu se zapaziti i aperiodična dinamička stanja odnosno haos. Poseban oblik haosa predstavljaju intermitentne oscilacije odnosno intermitentan haos. Intermitentan haos je ono haotično stanje gde se dva kvalitativno različita dinamička stanja naizmenicno i haotično smenjuju, pri konstantnim vrednostima kontrolnih parametara. Kao takav uočen je u mnogim složenim nelinearnim sistemima mada su saznanja o intermitentnim stanjima u oksihalogenidnim sistemima veoma skromna. Intermitentan haos, koji je u okviru ove teze eksperimentalno generisan, predstavlja haotičnu i naizmeničnu smenu intervala oscilacija velikih amplituda i intervala oscilacija malih amplituda. Za eksperimentalno praćenje intermitentnog haosa u ovoj tezi je korišćena potenciometrijska metoda, koja se inače široko primenjuje za praćenje dinamike hemijskih oscilatora. U oba oksihalogenidna sistema, obuhvaćena tezom, intermitentne oscilacije su uočene u zatvorenom i otvorenom reaktoru, i to u uzanom intervalu kontrolnih parametara u Bray-Liebhafsky sistemu i u uzanom opsegu koncentracija hemijskog perturbatora u Briggs-Rauscher sistemu. Kako bi se omogućila kvantitativna analiza dobijenih rezultata u okviru teze su razvijene i nove metode analize eksperimentalno dobijenog intermitentnog haosa. Pored toga pojedini rezultati su analizirani i primenom numeričkih metoda, poput onih koja se često koriste u analizi haosa, i to Poincaré-ove mape, Lyapunov-ljevi eksponenti i autokorelaciona metoda.

Oscillatory dynamic states are very common in natural processes and therefore very important for existence of the living world. Complex natural processes have numerous species that interact between one another in different manners, and so they are very complicated, or almost impossible, for detailed experimental investigations, so principal phenomena sould be examined in simpler chemical oscillators. Such systems are oxi-halide oscillators. The most famous oxi-halide oscillators are Bray-Liebhafsky and Briggs-Rauscher and they are the object of study in this thesis. In the narrow part of the oscillatory region, aperiodic dynamic states or chaos can be found. Intermittent oscillations or intermittent chaos represents a specific form of the chaotic state. Intermittent chaos is considered a chaotic state where transition between two qualitatively different dynamic states occurs randomly and wherein control parameters are constant. As such it was found in many complex nonlinear systems, however knowledge about intermittent states in oxi-halide systems are very modest. Experimentally generated intermittent chaos, within this thesis, represents dynamic state where intervals of high-amplitude oscillations chaotically alternate with intervals of low-amplitude oscillations. For experimental recording of the intermittent chaos, within this thesis, a potentiometric method was used. This method is widely used to follow the dynamics of the chemical oscillators. In this thesis, in both oxi-halide systems, intermittent oscilations were found in open and in closed reactor. Namely, intermitent oscillations were found in narrow interval of control parameters in Bray-Liebhafsky and in narrow range of concentrations of the chemical perturbator in Briggs-Rauscher reaction system. In order to allow quantitative analysis of obtained results, in this thesis new methods of the analysis of the experimentaly obtained intermittent states are developed. Besides, some results were analysed by numerical methods like Poincaré maps, Lyapunov exponents and autocorrelation function since those methods are often used in the analysis of chaos.