Study of q-dependent self and collective intermediate scattering functionsof magnetic chains in a quasi-two-dimensional aqueous solution

We studied the scattering wave number q-dependent self and collective inter mediate scattering functions. fs(q, t) and f(C)(q, t), of strongly interact ing tracer magnetic chains in a quasi-two-dimensional aqueous solution for different external magnetic fields, H, ranging from 8 Oe to 25 Oe. The q va lues were changed from 0.4q(o), to 2.4q(o), where q(o) is the position of t he first peak of the static structure factor S(g). We calculated f(S)(q, t) and f(C)(q, t) directly from the positions of the magnetic chains at diffe rent times ri(t), which were measured by using a microscope image analysis technique. Both f(S)(q, t) and fc(q t) were fitted to the stretched exponen tial form f(q. t) = exp[-(t/r)(beta)] with two fitting parameters, tau and beta. We found from 7(q) and beta (q) with different H strengths that the c ollective behavior of magnetic chains was related to S(q).