FIG. 3.

LIBS emission spectrum of Escherichia coli after various treatments and resuspended in distilled water. The spectrum was averaged over 25 laser shots at the surface of sample. Emission from the plasma was collected 50 ns after the laser pulse with an integration time of 700 μs in helium as background gas. (a) Laser pulses 150 fs long operating at 775 nm with pulse energy 1.4 mJ per pulse were used as excitation source. (b) Laser pulses 10 ns long operating at 1064 nm with pulse energy 20 mJ per pulse were used as excitation source.