Laser ablation of aqueous solutions with spatially homogeneous and heterogeneous absorption

Substrate temperature dependence of the structure of polythiophene thin films obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE)

“…The spectrum of the violet sample PTh deposited by the MAPLE technique on the hot substrate (T≈ 423K, trace b) shows a maximum at 560 nm (≈2.2 eV), with a red shift of around 70 nm with respect to the value shown for the PTc in the solid state and to the values 10 usually reported for the sample in solution.…”

“…If, as in our case, the solvent is almost transparent to laser radiation, which is absorbed by the solute molecules, due to low concentration of the latter, we have a highly non homogeneous light absorption. Laser evaporation of a frozen dilute solution of an absorbing solute in a transparent solvent can be assumed similar to laser ablation of a solution with spatially heterogeneous absorption [10]: the ablation efficiency of the heterogeneous solution is higher by more than one order of magnitude with respect to homogeneous absorption (as in PLD). This implies that using MAPLE technique it is possible to reduce laser pulse energy by one order of magnitude thus greatly reducing the negative effects of laser irradiation.…”

Effects of heterogeneous absorption of laser radiation in biotissue ablation: Characterization of ablation of fat with a pulsed CO2 laser

“…It was shown experimentally that the ablation threshold of a heterogeneously absorbing solution was 3-4 times lower than that of a homogeneously absorbing medium having an absorption coefficient similar to the average absorption coefficient of the solution with heterogeneous absorption [9]. If we replace 1.064 m with 10.6 m irradiation, the structure of fresh fat accommodates this model of heterogeneous absorption, except that carbon particles are replaced by water ''lakes'' ( a ‫ס‬ 829 cm −1 ), embedded in dry fat is ( a ‫ס‬ 1 cm −1 ) (Fig.…”

“…The heterogeneity of absorption coefficients in fresh fat causes local overheating of microareas where water is present. This local overheating and vaporization of water causes fat to be ejected as nonuniformly heated droplets [9]. Conversely, dermal ablation is primarily a tissue vaporization process.…”

Frozen Microemulsions for MAPLE Immobilization of Lipase

“…A vacuum system pumps away the matrix molecules, while the guest material deposits onto the substrate. The matrix absorbs most of the laser radiation giving a softer ejection mechanism with respect to pulsed laser deposition (PLD), hence transferring delicate molecules from the target to the substrate in undamaged form [2,3]. Due to such attributes, MAPLE technique has been successfully used to deposit several proteins in an undamaged and functional form [4][5][6][7][8].…”