Wavelength-selective vibrationally excited photodesorption with tunable IR sources

We present an overview of IR laser resonant desorption (LRD) studies with special focus on recent developments by our group. The resonant character of the laser desorption process mediated by O-H, C-H, and N-H vibrational modes in the 3 mu m spectral range has been investigated on ice, PAH and ammonia samples, respectively. The desorption of cryogenic binary mixtures is also presented. An interesting wavelength-selective effect has been found by comparative IR/visible or IR/IR irradiation studies. At higher fluences and/or analyte concentration values a loss of selectivity occurs, with extensive co-desorption of both components and clustering phenomena. Insights on the desorption mechanisms involved are presented through an ejecta velocity distribution study. Finally, possible technological and analytical potentialities are discussed, in the fields of IR-MALDI, LRD depth profiling, pulsed laser cleaning and selective analysis of complex samples.