Physical Electronics Inc.

East Gull Lake, MN, United States

Physical Electronics Inc.

East Gull Lake, MN, United States
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Ogrinc Potocnik N.,Maastricht University | Fisher G.L.,Physical Electronics Inc. | Prop A.,Maastricht University | Heeren R.M.A.,Maastricht University
Analytical Chemistry | Year: 2017

Matrix-enhanced secondary ion mass spectrometry (ME-SIMS) has overcome one of the biggest disadvantages of SIMS analysis by providing the ability to detect intact biomolecules at high spatial resolution. By increasing ionization efficiency and minimizing primary ion beam-induced fragmentation of analytes, ME-SIMS has proven useful for detection of numerous biorelevant species, now including peptides. We report here the first demonstration of tandem ME-SIMS for de novo sequencing of endogenous neuropeptides from tissue in situ (i.e., rat pituitary gland). The peptide ions were isolated for tandem MS analysis using a 1 Da mass isolation window, followed by collision-induced dissociation (CID) at 1.5 keV in a collision cell filled with argon gas, for confident identification of the detected peptide. Using this method, neuropeptides up to m/z 2000 were detected and sequenced from the posterior lobe of the rat pituitary gland. These results demonstrate the potential for ME-SIMS tandem MS development in bottom-up proteomics imaging at high-spatial resolution. © 2017 American Chemical Society.

Fisher G.L.,Physical Electronics Inc. | Hammond J.S.,Physical Electronics Inc. | Bryan S.R.,Physical Electronics Inc. | Larson P.E.,Physical Electronics Inc. | Heeren R.M.A.,Maastricht University
Microscopy and Microanalysis | Year: 2017

We present the first demonstration of a general method for the chemical characterization of small surface features at high magnification via simultaneous collection of mass spectrometry (MS) imaging and tandem MS imaging data. High lateral resolution tandem secondary ion MS imaging is employed to determine the composition of surface features on poly(ethylene terephthalate) (PET) that precipitate during heat treatment. The surface features, probed at a lateral resolving power of<200 nm using a surface-sensitive ion beam, are found to be comprised of ethylene terephthalate trimer at a greater abundance than is observed in the surrounding polymer matrix. This is the first chemical identification of PET surface precipitates made without either an extraction step or the use of a reference material. The new capability employed for this study achieves the highest practical lateral resolution ever reported for tandem MS imaging. © Microscopy Society of America 2017

PubMed | Physical Electronics Inc. and Maastricht University
Type: Journal Article | Journal: Analytical chemistry | Year: 2016

We report a method for the unambiguous identification of molecules in biological and materials specimens at high practical lateral resolution using a new TOF-SIMS parallel imaging MS/MS spectrometer. The tandem mass spectrometry imaging reported here is based on the precise monoisotopic selection of precursor ions from a TOF-SIMS secondary ion stream followed by the parallel and synchronous collection of the product ion data. Thus, our new method enables simultaneous surface screening of a complex matrix chemistry with TOF-SIMS (MS(1)) imaging and targeted identification of matrix components with MS/MS (MS(2)) imaging. This approach takes optimal advantage of all ions produced from a multicomponent sample, compared to classical tandem mass spectrometric methods that discard all ions with the exception of specific ions of interest. We have applied this approach for molecular surface analysis and molecular identification on the nanometer scale. High abundance sensitivity is achieved at low primary ion dose density; therefore, one-of-a-kind samples may be relentlessly probed before ion-beam-induced molecular damage is observed.

Barbey R.,Ecole Polytechnique Federale de Lausanne | Barbey R.,University of Sydney | Laporte V.,Center Interdisciplinaire Of Microscopie Electronique | Alnabulsi S.,Physical Electronics Inc. | Klok H.-A.,Ecole Polytechnique Federale de Lausanne
Macromolecules | Year: 2013

Surface-initiated polymerization represents a versatile strategy to modify a diverse range of materials with thin, functional polymer coatings. While in many cases the desired functional groups can be directly incorporated via (co)polymerization of the appropriate monomer(s), other functional groups are incompatible with the polymerization strategies that are commonly used to grow polymer brushes and can only be introduced by postpolymerization modification. Determining the local concentration and spatial distribution of these functional groups in postmodified brushes is a challenging task but could help to optimize the design and properties of these polymer coatings. This article reports on the use of X-ray photoelectron spectroscopy (XPS) combined with C60 cluster ion sputtering to address this challenge. Poly(glycidyl methacrylate) (PGMA) brushes prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) were used as a model platform and were postmodified with propylamine and bovine serum albumin (BSA). The XPS depth-profiling experiments showed that the small propylamine molecules were essentially homogeneously distributed throughout the brush, with the exception of the top few nanometers, which were enriched in propylamine moieties. It was also demonstrated that the amount of propylamine introduced within the polymer brush increased with increasing the postpolymerization reaction time, while no concentration gradients could be observed, indicative of a fast diffusion of the propylamine through the polymer brush layer. On the other hand, XPS depth-profiling experiments performed on polymer brushes that were postmodified with BSA revealed that this protein was only localized in the topmost layers of the polymer coating, which reflects the steric hindrance by the dense polymer brush that prevents efficient diffusion of these large molecules. Together, the results of these experiments demonstrate that XPS depth-profiling combined with C60 cluster ion sputtering is an efficient and powerful means to study the distribution of functionalities incorporated within a polymer brush layer by postpolymerization modification reactions. © 2013 American Chemical Society.

Miyayama T.,ULVAC PHI Inc. | Sanada N.,ULVAC PHI Inc. | Suzuki M.,ULVAC PHI Inc. | Hammond J.S.,Physical Electronics Inc. | And 2 more authors.
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films | Year: 2010

X-ray photoelectron spectroscopy depth profiling of polyimide thin films on silicon substrates using an Ar cluster ion beam results in an extremely low degradation of the polyimide chemistry. In the range from 2.5 to 20 kV, a lower cluster ion energy produces a lower sputter induced damage to the polymer and results in an improved polyimide to silicon interface width. The sputtering rates of the polyimide are found to increase exponentially with an increase in the Ar cluster ion energy. © 2010 American Vacuum Society.

PubMed | Physical Electronics Inc. and BAM Federal Institute of Materials Research and Testing
Type: Journal Article | Journal: Biointerphases | Year: 2016

The growing interest in artificial bioorganic interfaces as a platform for applications in emerging areas as personalized medicine, clinical diagnostics, biosensing, biofilms, prevention of biofouling, and other fields of bioengineering is the origin of a need for in detail multitechnique characterizations of such layers and interfaces. The in-depth analysis of biointerfaces is of special interest as the properties of functional bioorganic coatings can be dramatically affected by in-depth variations of composition. In worst cases, the functionality of a device produced using such coatings can be substantially reduced or even fully lost.

Amit I.,Israel Electric | Givan U.,Northwestern University | Givan U.,Max Planck Institute of Microstructure Physics | Connell J.G.,Northwestern University | And 4 more authors.
Nano Letters | Year: 2013

Controlling axial and radial dopant profiles in nanowires is of utmost importance for NW-based devices, as the formation of tightly controlled electrical junctions is crucial for optimization of device performance. Recently, inhomogeneous dopant profiles have been observed in vapor-liquid-solid grown nanowires, but the underlying mechanisms that produce these inhomogeneities have not been completely characterized. In this work, P-doping profiles of axially modulation-doped Si nanowires were studied using nanoprobe scanning Auger microscopy and Kelvin probe force microscopy in order to distinguish between vapor-liquid-solid doping and the vapor-solid doping. We find that both mechanisms result in radially inhomogeneous doping, specifically, a lightly doped core surrounded by a heavily doped shell structure. Careful design of dopant modulation enables the contributions of the two mechanisms to be distinguished, revealing a surprisingly strong reservoir effect that significantly broadens the axial doping junctions. © 2013 American Chemical Society.

Miyayama T.,ULVAC PHI Inc. | Sanada N.,ULVAC PHI Inc. | Bryan S.R.,Physical Electronics Inc. | Hammond J.S.,Physical Electronics Inc. | Suzuki M.,ULVAC PHI Inc.
Surface and Interface Analysis | Year: 2010

An Ar Gas Cluster Ion Beam (GCIB) has been shown to remove previous Ar + ion beam-induced surface damage to a bulk polyimide (PI) film. After removal of the damaged layer with a GCIB sputter source, XPS measurements show minor changes to the carbon, nitrogen and oxygen atomic concentrations relative to the original elemental bulk concentrations. The GCIB sputter depth profiles showed that there is a linear relationship between the Ar+ ion beam voltage within the range from 0.5 to 4.0 keV and the dose of argon cluster ions required to remove the damaged layer. The rate of recovery of the original PI atomic composition as a function of GCIB sputtering is similar for carbon, nitrogen and oxygen, indicating that there was no preferential sputtering for these elements. The XPS chemical state analysis of the N 1s spectra after GCIB sputtering revealed a 17% damage ratio of altered nitrogen chemical state species. Further optimization of the GCIB sputtering conditions should lead to lower nitrogen damage ratios with the elemental concentrations closer to those of bulk PI. Copyright © 2010 John Wiley & Sons, Ltd.

Iida S.-I.,ULVAC PHI Inc. | Miyayama T.,ULVAC PHI Inc. | Sanada N.,ULVAC PHI Inc. | Suzuki M.,ULVAC PHI Inc. | And 2 more authors.
Surface and Interface Analysis | Year: 2011

The introduction of C60 + as a sputter ion beam for ToF-SIMS has made it possible to acquire molecular depth profiles on a wide variety of polymers. However, previous studies have indicated that certain classes of polymers undergo sputter-induced damage when bombarded with C 60 + that prevents obtaining stable molecular secondary ion signals as a function of depth. A number of different analytical parameters have been previously explored in attempts to improve depth profiling of these polymer classes. In this study, the effect of C60 + incident angle on the ability to depth profile polycarbonate (PC) and polystyrene (PS) was investigated at angles from 48° to 76° with respect to the sample normal. This study indicates that the highest sputtering angle provided the best conditions for molecular depth profiling. Copyright © 2010 John Wiley & Sons, Ltd.

Watson D.G.,Physical Electronics Inc. | Larson P.E.,Physical Electronics Inc. | Paul D.F.,Physical Electronics Inc. | Negri R.E.,Physical Electronics Inc.
Surface and Interface Analysis | Year: 2012

An experimental method that increases the analyzer resolution of cylindrical mirror analyzer CMA-based Auger spectrometers is described. By means of electrically biasing the sample, the effective energy resolution obtainable from the CMA instrument is improved from the native 0.5 to 0.1% or even better for higher kinetic energy Auger transitions. In addition, the maximum kinetic energy Auger transition observable by the CMA Auger instrument is increased from 3200 to 5700 eV, in the current realization. It is also shown that the sensitivity of the energy scale calibration to sample working distance with respect to the analyzer is simultaneously reduced, making the method suitable for chemical surface analysis. The biasing is accomplished using a special sample holder with electronics and software that can be added to an existing instrument. The overall capability of the Auger instrument for chemical analysis is, therefore, increased, while preserving all the analytical functionality and features of the CMA. © 2011 John Wiley & Sons, Ltd.

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