Velocity distribution of molecular fragments from polymethylmethacrylate irradiated with UV laser pulses

Abstract

Polymethylmethacrylate samples are irradiated with pulses from an ArF excimer laser at λ=193 nm. The velocities of ablated particles are measured with the use of a quadrupole mass spectrometer. For laser fluences <120 mJ/cm2 we observe thermal, Maxwell–Boltzmann velocity distributions. The photofragments possess a common temperature which increases with fluence to values as high as 3000 K.