Ultra-short laser ablation of biological tissue

The investigation of the mechanism of ultra-short laser ablation process of biological tissue represents one of the challenging subjects over the last couple of years. The femtosecond laser pulses are very well suited for high precision surgery, due to its low thermal and mechanical stress. The current research was emphasized on the examination of the interaction mechanism of high intensity ultra-short ferntosecond and nanosecond laser pulses with hard biological tissue material (tooth, bones). It was established that femtosecond ablation works well for ablation of complex biological molecule systems. A more detailed view was taken by investigating the ablation dynamics at several wavelengths. The precise examination of the mass spectra of laser ablation with 193nm and 800nm introduces the way of altering the chemical composition of the ablated tissue. In general, it was found that ablation with ultra-short (femtosecond) pulses at 800nm radiation yields the highest number of characteristic ions. To better understand the interaction mechanism we have performed post-ionization experiments. It was of main importance to succeed to establish efficient ionization of the organic molecules with minimal fragmentation. This work demonstrates sensitivity of the time-of-flight (TOF) technique and the great potential of the laser ablation/ultra-short laser secondary neutrals mass spectroscopy (LA/US-LSNMS) method in increasing the information content of biomolecular mass spectra.