Laser-induced transfer of nanoparticles for gas-phase analysis

Laser pulse duration dependence of blister formation on back-radiated Ti thin films for BB-LIFT

“…Whilst MALDI and electrospray methods are effective for producing beams of charged molecules and have revolutionised the mass spectrometry of large biomolecules, they harbour some significant drawbacks, such as difficulties in quantification, or the need to find an appropriate solution or matrix material that may also then be present in the produced beam, and neither of them are particularly suitable for preparing well-defined beams of neutral species. LIAD can be applied to any molecule that can be deposited on the metal foil and is thus more general; however, there is some controversy concerning the desorption mechanism and the extent to which molecules may be heated and fragment during the desorption process [6].…”

“…More recently, it has been used to produce beams of nanoparticles for gas phase analysis [6]. This technique has the same advantages as LIAD but allows a more controlled desorption due to the control over the thickness and properties of the intermediate layer.…”

“…This technique has the same advantages as LIAD but allows a more controlled desorption due to the control over the thickness and properties of the intermediate layer. A thin film of metal [6,7,10] or polymer [8,9] (used so far for depositing liquid inks) is deposited on a glass substrate and placed between the transparent substrate and the molecules of interest. The thin film absorbs the laser pulse thereby rapidly deforming into a blister that propels the particles or ink forward in a beam.…”

“…The technique has shown considerable promise for printing micro-scale patterns based on desorbed organic material [9,11,12] or nanoparticles [7]. However, there is some uncertainty concerning the method of blister formation and evidence for extensive heating of the metal film when using ns lasers [6], which could lead to thermal degradation of the desorbed nanoparticles and molecules. A comparison involving UV ns laser desorption of organic liquids using no intermediate layer, a thin metal layer and a thick polyimide layer did provide evidence of degradation in the first two cases but not with the thick polymer film [9].…”

“…1. The first, usually discussed in the context of thin metal film layers [6], involves rapid heating accompanied by deformation induced by the different thermal expansion coefficients of the metal film and the underlying substrate. The second, mainly discussed in the context of ns UV laser BB-LIFT of polyimide films [8], involves localised ablation at the interface between the polymer film and the underlying substrate.…”