Self-oscillating polymer chain in a laser field

We have investigated the dynamical behaviour of the rhythmic conformational change between the folded compact state and the unfolded state in a single polymer chain under thermodynamically open conditions. It is shown that the spontaneous rhythmic change in the conformation of a single polymer chain (T4DNA, 166 kbp, contour length: 56 mum) is generated using a focused continuous wave (CW) Nd : YAG laser beam (wavelength lambda = 1064 nm), where the focused laser beam plays a dual role, both trapping a polymer chain at the focus and creating a temperature gradient around the focus. Furthermore, the whole process of the rhythmic conformational change: the course of melting, nucleation and growth between the folded and unfolded states has been clarified. The rhythmic change in the conformation is discussed in terms of the limit-cycle oscillation driven by the dissipation of the photon energy.