Energy absorption and emission of harmonics by clusters subject to intense short laser pulses

Experimental and theoretical achievements in studies of atomic and metal clusters interacting with short intense infrared laser pulses are reviewed. The focus is made on the theoretical concepts describing the energy transfer from the laser field to the cluster nanoplasma and emission of laser harmonics from it. Both effects are considered assuming the collisionless regime, where the interaction of nanoplasma electrons with the self-consistent field dominates the individual collisions. The pivotal role of nonlinear resonances is underlined and described in detail. Possible ways for a further development of the theory and experimental perspectives are briefly discussed.