2.4. LIBS instrumental optimization
The influence of the LIBS instrumental parameters on the analytical
signal was checked using 13 mm wood pellets obtained by
pressing 0.5 g of pulverized material by 8 ton cm2 for 5 min.
Spot size was checked from 35 to 140 lm, the laser repetition rate
from 5 to 20 Hz, laser energy from 5 to 25 mJ/pulse, accumulated
pulses from 5 to 200 and delay time from 0 to 0.4 ls. Sample