LASER-INDUCED ABLATION THROUGH NANOMETER-SIZED TIP APERTURES - MECHANISTIC ASPECTS

Mechanisms for laser ablation of rhodamine dye thin films through nano meter-sized tip apertures commonly used for scanning near-field optica l microscopy (SNOM) are discussed. Experiments and observations are pr esented that refute a mechanism based on transient tip elongation. Bal listic heat transfer is found to be insufficient for ablation of ionic solids such as rhodamine dyes. The most likely mechanism for creation of the nanoindentations on rhodamine films is photothermal ablation. It is further demonstrated that rhodamine is sublimating upon irradiat ion, is transported over considerable distances, and is redeposited. T his may permit laser ablation through SNOM tips for nanosampling and n anoanalytical methods.