IR wavelength-selective laser desorption via O-H and C-H stretching modes

摘要

We present new results on wavelength-selective desorption of solid samples using the resonant interaction between the laser beam and the bulk. The experimental set-up is based on the coupling of three techniques: laser desorption in the near-infrared (IR) (2.7-4 mu m) with a tunable IR optical parametric oscillator (OPO), UV multi-photon ionization, and reflectron time-of-flight mass spectrometry. The resonant character of the laser desorption process has been investigated for an ice/polycyclic, aromatic hydrocarbon (PAH) mixture, by excitation of the O-H and C-H stretching modes. Highly preferential desorption has been evidenced, with exclusive desorption of water and PAH molecules at the O-H and C-H resonances, respectively. Potential analytical (e.g. selective analysis of complex samples) and technological (e.g. dry laser cleaning, DLC) applications are discussed. (c) 2006 Elsevier B.V. All rights reserved.