FIAS Scientific Report 2011 - Frankfurt Institute for Advanced Studies ...

Laser-induced acoustic desorption
Collaborators: A.V. Yakubovich 1 , A.V. Solov’yov 1 , I.A. Solov’yov 2
1 Frankfurt Institute for Advanced Studies, 2 UIUC, Urbana, USA
Short description:
Laser-induced acoustic desorption (LIAD) is a procedure of gentle lifting of large neutral biomolecules into
the gas phase. In LIAD experiments the biomolecules are deposited on a surface of a relatively thin (∼ 10µm)
metallic foil. The back surface of the foil is irradiated by the laser pulse. The energy of the laser is adsorbed
by the material of the foil which consequently causes the propagation of acoustic and thermal waves. The
propagating waves induce vibration of the foil material which stimulates the emission of biomolecules from the
foil surface to the gas phase.
Main results:
• By means of molecular dynamics simulations
we have investigated the desorption process of
lysine amino acids from the surface of the nickel
foil.
• The desorption rate of the amino acids as a
function of the surface acceleration has been
analysed. It was shown that the desorption rate
has an exponential dependence on the value of
the substrate acceleration.
• The final group velocities of the desorbed
molecules were analysed. It was shown that in
the coordinate frame moving with the speed of
the substrate at the initial moment of time, the
velocities of the molecules are inversely proportional
to the substrate acceleration.
Figure 1. Evaporation of a cluster of several lysine
residues from the surface of a nickel foil. The evaporation
is caused by the foil acceleration.
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Figure 2. The number of evaporated lysine
residues as a function of time after the start of
nickel foil acceleration. Symbols show the results
of molecular dynamics simulations corresponding
to different values of foil acceleration. Solid lines
show the theoretical curves corresponding to the
results of molecular dynamics simulations. The
legend indicates the values of acceleration used in
the simulations.