The role of inertial and spatial confinement in laser interaction with organic materials

Short-pulse laser irradiation of organic material performed under conditions of inertial or spatial confinement can result in laser damage or material ejection (ablation) at relatively low laser fluences. A computational investigation of the mechanisms of the efficient transformation of the deposited laser energy into the energy of material ejection is used in this work to discuss a number of potential applications of the regime of confined laser ablation. In particular, we show that a direct irradiation of a bulk organic sample by a laser pulse performed in the regime of stress confinement can lead to the ejection of a layer of a relatively intact material with thickness determined by the laser penetration depth and fluence. Further irradiation of the spalled layer by an intense femtosecond laser pulse leads to efficient emission of picosecond bunches of energetic ions directed toward the target. In another example, a controlled deposition of functional organic molecules into a designated region of a polymer substrate is achieved by laser irradiation of a microscopic amount of molecular substance spatially confined in the tip of a micropipette.