  The most attractive feature of dusty plasmas is the possibility to create
strong correlations at room temperatures. At the same time, these plasmas allow
for a precise diagnostics with single-particle resolution. From such
measurements, the structural properties of finite two-dimensional (2D) clusters
and three-dimensional (3D) spherical crystals in nearly harmonic traps-Yukawa
balls-have been explored in great detail. Their structural properties-the shell
compositions and the order within the shells-have been investigated and good
agreement to theoretical predictions was found. Open questions on the agenda
are the excitation behavior, the structural changes, and phase transitions that
occur at elevated temperature.
  In order to increase the dust temperature in the experiment various
techniques have been used. Among them, laser heating appears to have unique
capabilities because it affects only the dust particles, leaving the lighter
plasma components unchanged. Here we report on recent experimental results
where laser heating methods were further improved and applied to finite 2D and
3D clusters. Comparing to simulations, we demonstrate that this indeed allows
to increase the temperature in a controlled manner. For the analysis of
thermodynamics and phase transitions in these finite systems, we present
theoretical and experimental results on the basis of the instantaneous normal
modes, pair distribution function and the recently introduced
center-two-particle distribution function.
