Public Abstract

DE-FG02-06ER15803: CHEMICAL IMAGING WITH CLUSTER ION BEAMS AND LASERS

Award Status: Inactive

Institution: The Pennsylvania State University, University Park, PA
UEI: NPM2J7MSCF61
DUNS: 003403953

Most Recent Award Date: 02/23/2016
Number of Support Periods: 10
PM: Wilk, Philip

Current Budget Period: 01/01/2016 - 12/31/2016
Current Project Period: 01/01/2016 - 12/31/2016
PI: Winograd, Nicholas

Supplement Budget Period: N/A

Public Abstract

Project Summary/Abstract Chemical Imaging with Cluster Ion Beams and Lasers PI: Nicholas Winograd, Penn State University The objective of this renewal proposal to the Department of Energy is to create a novel nanoscale three-dimensional molecule-specific imaging capability for characterization of a wide range of materials. The basic idea is to desorb ionized molecules into a mass spectrometer for chemical identification using a focused cluster ion beam. A two-dimensional image is created by deflecting the beam in a raster pattern across the sample, collecting mass spectra on the fly. Moreover, since the ion/solid interaction leaves the surface relatively undamaged, images may be taken as the molecules are being removed. Stacking these images together creates three dimensional information. This unique strategy allows chemical identification of molecules in the near surface region of the target with a lateral resolution of a few hundred nanometers, and a depth resolution of ~10 nanometers. The fundamental barrier to expanding the application of this tool is the need for extreme sensitivity. The number of molecules available for desorption is limited as the probe size is reduced, and the efficiency of ionization is generally low. Our research is aimed toward increasing the efficiency of both the desorption step and the ionization step by optimizing the chemical and physical properties of the cluster ion source, and by implementing a new laser-based approach, strong field ionization (SFI in the IR) for increasing ionization efficiency of the desorbed molecules. Preliminary experiments suggest that an overall sensitivity increase of 10 – 1000x is expected. Specific goals are (1) to demonstrate the generality of SFI using femtosecond IR pulsed lasers to post-ionize sputtered molecules with the least amount of induced fragmentation, (2) to construct a novel multi-pass optic to more effectively sample the ablation plume created by the cluster ion beam, (3) to utilize the chemistry of gas cluster ion beams containing 1000 – 10000 species to improve desorption ionization efficiency and probe the mechanism of this phenomenon using SFI, (4) for the first time, to allow images to be acquired quantitatively by separating the desorption step from the ionization step and characterizing complex multicomponent and multilayer structures. A critical part of this research is (1) to demonstrate the unique capabilities of our technology by unraveling the architecture of complex aerosol particles with heterogeneous in-depth compositions and (2) to reveal the distribution of hydrocarbons and long chain fatty acids in b. braunii algal colonies at the single cell level, and elucidate the mechanism of hydrocarbon excretion. In general, we expect this major jump in 3- dimensional imaging capability will lead to application in many areas of energy-related research that have heretofore remained insoluble.

Project Summary/Abstract

Chemical Imaging with Cluster Ion Beams and Lasers

PI: Nicholas Winograd, Penn State University

The objective of this renewal proposal to the Department of Energy is to create a novel nanoscale three-dimensional molecule-specific imaging capability for characterization of a wide range of materials. The basic idea is to desorb ionized molecules into a mass spectrometer for chemical identification using a focused cluster ion beam. A two-dimensional image is created by deflecting the beam in a raster pattern across the sample, collecting mass spectra on the fly. Moreover, since the ion/solid interaction leaves the surface relatively undamaged, images may be taken as the molecules are being removed. Stacking these images together creates three dimensional information. This unique strategy allows chemical identification of molecules in the near surface region of the target with a lateral resolution of a few hundred nanometers, and a depth resolution of ~10 nanometers. The fundamental barrier to expanding the application of this tool is the need for extreme sensitivity. The number of molecules available for desorption is limited as the probe size is reduced, and the efficiency of ionization is generally low. Our research is aimed toward increasing the efficiency of both the desorption step and the ionization step by optimizing the chemical and physical properties of the cluster ion source, and by implementing a new laser-based approach, strong field ionization (SFI in the IR) for increasing ionization efficiency of the desorbed molecules. Preliminary experiments suggest that an overall sensitivity increase of 10 – 1000x is expected.

Specific goals are (1) to demonstrate the generality of SFI using femtosecond IR pulsed lasers to post-ionize sputtered molecules with the least amount of induced fragmentation, (2) to construct a novel multi-pass optic to more effectively sample the ablation plume created by the cluster ion beam, (3) to utilize the chemistry of gas cluster ion beams containing 1000 – 10000 species to improve desorption ionization efficiency and probe the mechanism of this phenomenon using SFI, (4) for the first time, to allow images to be acquired quantitatively by separating the desorption step from the ionization step and characterizing complex multicomponent and multilayer structures. A critical part of this research is (1) to demonstrate the unique capabilities of our technology by unraveling the architecture of complex aerosol particles with heterogeneous in-depth compositions and (2) to reveal the distribution of hydrocarbons and long chain fatty acids in b. braunii algal colonies at the single cell level, and elucidate the mechanism of hydrocarbon excretion. In general, we expect this major jump in 3- dimensional imaging capability will lead to application in many areas of energy-related research that have heretofore remained insoluble.