Before revision: Regarding the creation of indentations, or pits, non-crosslinked polymers retain a low glass temperature, around 120 °C for PMMAMamin Rugar "Thermomechanical writing with an atomic force microscope tip" Applied Physics Letters (1992) and if the probe tip is heated to above the glass temperature, it leaves a small indentation.
After revision: Regarding the creation of indentations, or pits, non-crosslinked polymers retain a low glass temperature, around 120 °C for PMMAMamin PMMA and if the probe tip is heated to above the glass temperature, it leaves a small indentation.