Design and performance of an instrument for soft landing of biomolecular ions on surfaces.
A new ion deposition apparatus was designed and constructed in our laboratory. Our research objectives were to investigate interactions of biomolecules with hydrophilic and hydrophobic surfaces and to carry out exploratory experiments aimed at highly selective deposition of spatially defined and uniquely selected biological molecules on surfaces. The apparatus includes a high-transmission electrospray ion source, a quadrupole mass filter, a bending quadrupole that deflects the ion beam and prevents neutral molecules originating in the ion source from impacting the surface, an ultrahigh vacuum (UHV) chamber for ion deposition by soft landing, and a vacuum lock system for introducing surfaces into the UHV chamber without breaking vacuum. Ex situ analysis of surfaces following soft landing of mass-selected peptide ions was performed using 15 keV Ga+ time-of-flight secondary ion mass spectrometry and grazing incidence infrared reflection-absorption spectroscopy. It is shown that these two techniques are highly complementary methods for characterization of surfaces prepared with a range of doses of mass-selected biomolecular ions. We also demonstrated that soft landing of peptide ions on surfaces can be utilized for controlled preparation of peptide films of known coverage for fundamental studies of matrix effects in SIMS.
Pacific Northwest National Laboratory, Fundamental Science Directorate and Environmental Molecular Sciences Laboratory, Richland, WA 99352, USA.
Omar
O
Hadjar
Peng
P
Wang
Jean H
JH
Futrell
Yury
Y
Dessiaterik
Zihua
Z
Zhu
James P
JP
Cowin
Martin J
MJ
Iedema
Julia
J
Laskin
D003198:Computer Simulation; D007477:Ions / Q000737:chemistry; D013058:Mass Spectrometry; D010455:Peptides / Q000737:chemistry*; D013499:Surface Properties
D007477:Ions; D010455:Peptides