Year: 2014
Type: article
Abstract: Electron-hole separation following hard X-ray absorption during diffraction analysis of soft materials under cryogenic conditions produces substantial local electric fields visualizable by second harmonic generation (SHG) microscopy. Monte Carlo simulations of X-ray photoelectron trajectories suggest the formation of substantial local electric fields in the regions adjacent to those exposed to X-rays, indicating a possible electric-field-induced SHG (EFISH) mechanism for generating the observed signal. In studies of amorphous vitreous solvents, analysis of the SHG spatial profiles following X-ray microbeam exposure was consistent with an EFISH mechanism. Within protein crystals, exposure to 12-keV (1.033-Å) X-rays resulted in increased SHG in the region extending ∼ 3 μm beyond the borders of the X-ray beam. Moderate X-ray exposures typical of those used for crystal centering by raster scanning through an X-ray beam were sufficient to produce static electric fields easily detectable by SHG. The X-ray-induced SHG activity was observed with no measurable loss for longer than 2 wk while maintained under cryogenic conditions, but disappeared if annealed to room temperature for a few seconds. These results provide direct experimental observables capable of validating simulations of X-ray-induced damage within soft materials. In addition, X-ray-induced local fields may potentially impact diffraction resolution through localized piezoelectric distortions of the lattice.
Authors: Christopher M. Dettmar, Justin A. Newman, Scott J. Toth, Michael Becker, Robert F. Fischetti, Garth J. Simpson
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: G102163711, G107546177, G1286251239, G1313983767, TAS::89 0227::TAS RECOVERY; NEW: RECOVERY ACT - CENTER FOR DIRECT CATALYTIC CONVERSION OF BIOMASS TO BIOFUELS (C3BIO) -- EFRC; PI - MAUREEN CAROLINE, G1664757510, G2287611682, G262962599, G2784524989, G3075337988, G3076027529, G3135663181, G3152346458, G409777406, G426311843, TAS::89 0227::TAS RECOVERY; NEW: RECOVERY ACT - CENTER FOR DIRECT CATALYTIC CONVERSION OF BIOMASS TO BIOFUELS (C3BIO) -- EFRC; PI - MAUREEN CAROLINE, G498139845, G5387317844, G5607048534, G6566242307, Ultrafast Nonlinear Optical Approaches toward High-Throughput Membrane Protein Na, G6848031779, G6918803902, G7305522719, Nonlinear Optical Imaging for Guiding Protein Structure Determination, G7583137537, G7867766018, G8686948558, G969889393, G993149817
OpenAlex ID: W2163397997