Revealing the Elemental Distribution Within Latent Fingermarks Using Synchrotron Sourced X-Ray Fluorescence Microscopy

2019 ◽  
Author(s):  
Rhiannon Boseley ◽  
Buddhika Dorakumbura ◽  
Daryl L. Howard ◽  
martin de jonge ◽  
Mark J. Tobin ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Direct Detection ◽  
Detection Methods ◽  
Chemical Components ◽  
Light Sources ◽  
Elemental Distribution ◽  
X Ray ◽  
Organic Components ◽  
Mapping Techniques ◽  
Synchrotron Light Sources

<div><div><div><p>Fingermarks are an important form of crime-scene trace evidence; however, their usefulness may be hampered by a variation in response or a lack of robustness in detection methods. Understanding the chemical composition and distribution within fingermarks may help explain variation in latent fingermark detection with existing methods and identify new strategies to increase detection capabilities. The majority of research in the literature describes investigation of organic components of fingermark residue, leaving the elemental distribution less well understood. The relative scarcity of information regarding the elemental distribution within fingermarks is in part due to previous unavailability of direct, micron resolution elemental mapping techniques. This capability is now provided at third generation synchrotron light sources, where X-ray Fluorescence Microscopy (XFM) provides micron or sub-micron spatial resolution and direct detection with sub-μM detection limits. XFM has been applied in this study to reveal the distribution of inorganic components within fingermark residue, including endogenous trace metals (Fe, Cu, Zn), diffusible ions (Cl-, K+, Ca2+), and exogeneous metals (Ni, Ti, Bi). This study incorporated a multi-modal approach using XFM and Infrared Microspectroscopy (IRM) analyses to demonstrate co-localisation of endogenous metals within the hydrophilic organic components of fingermark residue. Additional experiments were then undertaken to investigate how sources of exogenous metals (e.g. coins and cosmetics) may be transferred to, and distributed within latent fingermarks. Lastly, this study reports a preliminary assessment of how environmental factors such as exposure to aqueous environments may effect elemental distribution within fingermarks. Taken together, the results of this study advance our current understanding of fingermark composition and its spatial distribution of chemical components, and may help explain detection variation observed during detection of fingermarks using standard forensic protocols.</p></div></div></div>

Revealing the Elemental Distribution Within Latent Fingermarks Using Synchrotron Sourced X-Ray Fluorescence Microscopy

2019 ◽  
Author(s):  
Rhiannon Boseley ◽  
Buddhika Dorakumbura ◽  
Daryl L. Howard ◽  
martin de jonge ◽  
Mark J. Tobin ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Direct Detection ◽  
Detection Methods ◽  
Chemical Components ◽  
Light Sources ◽  
Elemental Distribution ◽  
X Ray ◽  
Organic Components ◽  
Mapping Techniques ◽  
Synchrotron Light Sources

<div><div><div><p>Fingermarks are an important form of crime-scene trace evidence; however, their usefulness may be hampered by a variation in response or a lack of robustness in detection methods. Understanding the chemical composition and distribution within fingermarks may help explain variation in latent fingermark detection with existing methods and identify new strategies to increase detection capabilities. The majority of research in the literature describes investigation of organic components of fingermark residue, leaving the elemental distribution less well understood. The relative scarcity of information regarding the elemental distribution within fingermarks is in part due to previous unavailability of direct, micron resolution elemental mapping techniques. This capability is now provided at third generation synchrotron light sources, where X-ray Fluorescence Microscopy (XFM) provides micron or sub-micron spatial resolution and direct detection with sub-μM detection limits. XFM has been applied in this study to reveal the distribution of inorganic components within fingermark residue, including endogenous trace metals (Fe, Cu, Zn), diffusible ions (Cl-, K+, Ca2+), and exogeneous metals (Ni, Ti, Bi). This study incorporated a multi-modal approach using XFM and Infrared Microspectroscopy (IRM) analyses to demonstrate co-localisation of endogenous metals within the hydrophilic organic components of fingermark residue. Additional experiments were then undertaken to investigate how sources of exogenous metals (e.g. coins and cosmetics) may be transferred to, and distributed within latent fingermarks. Lastly, this study reports a preliminary assessment of how environmental factors such as exposure to aqueous environments may effect elemental distribution within fingermarks. Taken together, the results of this study advance our current understanding of fingermark composition and its spatial distribution of chemical components, and may help explain detection variation observed during detection of fingermarks using standard forensic protocols.</p></div></div></div>

scholarly journals Short X-ray pulses from third-generation light sources

2016 ◽  
Vol 23 (1) ◽  
pp. 141-151 ◽  
Author(s):  
A. G. Stepanov ◽  
C. P. Hauri
Keyword(s):  
Large Scale ◽  
Light Sources ◽  
Third Generation ◽  
Time Duration ◽  
Pulse Emission ◽  
Time Resolved ◽  
High Brightness ◽  
X Ray ◽  
Synchrotron Light ◽  
Synchrotron Light Sources

High-brightness X-ray radiation produced by third-generation synchrotron light sources (TGLS) has been used for numerous time-resolved investigations in many different scientific fields. The typical time duration of X-ray pulses delivered by these large-scale machines is about 50–100 ps. A growing number of time-resolved studies would benefit from X-ray pulses with two or three orders of magnitude shorter duration. Here, techniques explored in the past for shorter X-ray pulse emission at TGLS are reviewed and the perspective towards the realisation of picosecond and sub-picosecond X-ray pulses are discussed.

Generation of picosecond electron bunches in storage rings

2014 ◽  
Vol 21 (5) ◽  
pp. 961-967 ◽  
Author(s):  
Xiaobiao Huang ◽  
Thomas Rabedeau ◽  
James Safranek
Keyword(s):  
Storage Ring ◽  
Short Pulse ◽  
Storage Rings ◽  
High Repetition Rate ◽  
Light Sources ◽  
X Ray ◽  
Electron Bunches ◽  
Performance Challenges ◽  
Synchrotron Light Sources ◽  
Srf Cavities

Approaches to generating short X-ray pulses in synchrotron light sources are discussed. In particular, the method of using a superconducting harmonic cavity to generate simultaneously long and short bunches in storage rings and the approach of injecting short bunches from a linac injector into a storage ring for multi-turn circulation are emphasized. If multi-cell superconducting RF (SRF) cavities with frequencies of ∼1.5 GHz can be employed in storage rings, it would be possible to generate stable, high-flux, short-pulse X-ray beams with pulse lengths of 1–10 ps (FWHM) in present or future storage rings. However, substantial challenges exist in adapting today's high-gradient SRF cavities for high-current storage ring operation. Another approach to generating short X-ray pulses in a storage ring is injecting short-pulse electron bunches from a high-repetition-rate linac injector for circulation. Its performance is limited by the microbunching instability due to coherent synchrotron radiation. Tracking studies are carried out to evaluate its performance. Challenges and operational considerations for this mode are considered.

scholarly journals Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

2016 ◽  
Vol 23 (3) ◽  
pp. 685-693 ◽  
Author(s):  
Michael E. Rutherford ◽  
David J. Chapman ◽  
Thomas G. White ◽  
Michael Drakopoulos ◽  
Alexander Rack ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Dynamic Range ◽  
Short Pulse ◽  
European Synchrotron Radiation Facility ◽  
Light Sources ◽  
Time Resolved ◽  
X Ray ◽  
Short Pulse Duration ◽  
Wide Range ◽  
Synchrotron Light Sources

The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

Uridine as a new scavenger for synchrotron-based structural biology techniques

2017 ◽  
Vol 24 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Eva Crosas ◽  
Albert Castellvi ◽  
Isidro Crespo ◽  
Daniel Fulla ◽  
Fernando Gil-Ortiz ◽  
...  
Keyword(s):  
Structural Damage ◽  
Free Radical Scavenger ◽  
Protein Solutions ◽  
Radical Scavenger ◽  
Light Sources ◽  
Negative Effects ◽  
Buffer Solution ◽  
X Ray ◽  
Scavenging Effect ◽  
Synchrotron Light Sources

Macromolecular crystallography (MX) and small-angle X-ray scattering (SAXS) studies on proteins at synchrotron light sources are commonly limited by the structural damage produced by the intense X-ray beam. Several effects, such as aggregation in protein solutions and global and site-specific damage in crystals, reduce the data quality or even introduce artefacts that can result in a biologically misguiding structure. One strategy to reduce these negative effects is the inclusion of an additive in the buffer solution to act as a free radical scavenger. Here the properties of uridine as a scavenger for both SAXS and MX experiments on lysozyme at room temperature are examined. In MX experiments, upon addition of uridine at 1 M, the critical dose D 1/2 is increased by a factor of ∼1.7, a value similar to that obtained in the presence of the most commonly used scavengers such as ascorbate and sodium nitrate. Other figures of merit to assess radiation damage show a similar trend. In SAXS experiments, the scavenging effect of 40 mM uridine is similar to that of 5% v/v glycerol, and greater than 2 mM DTT and 1 mM ascorbic acid. In all cases, the protective effect of uridine is proportional to its concentration.

scholarly journals RefPlanets: Search for reflected light from extrasolar planets with SPHERE/ZIMPOL

2020 ◽  
Vol 634 ◽  
pp. A69 ◽  
Author(s):  
S. Hunziker ◽  
H. M. Schmid ◽  
D. Mouillet ◽  
J. Milli ◽  
A. Zurlo ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Direct Detection ◽  
Speckle Noise ◽  
Detection Methods ◽  
Integration Time ◽  
Light Sources ◽  
Post Processing ◽  
Photon Noise ◽  
Reflected Light ◽  
Blind Search

Aims. RefPlanets is a guaranteed time observation programme that uses the Zurich IMaging POLarimeter (ZIMPOL) of Spectro-Polarimetric High-contrast Exoplanet REsearch instrument at the Very Large Telescope to perform a blind search for exoplanets in wavelengths from 600 to 900 nm. The goals of this study are the characterisation of the unprecedented high polarimetic contrast and polarimetric precision capabilities of ZIMPOL for bright targets, the search for polarised reflected light around some of the closest bright stars to the Sun, and potentially the direct detection of an evolved cold exoplanet for the first time. Methods. For our observations of α Cen A and B, Sirius A, Altair, ɛ Eri and τ Ceti we used the polarimetricdifferential imaging (PDI) mode of ZIMPOL which removes the speckle noise down to the photon noise limit for angular separations ≿0.6′′. We describe some of the instrumental effects that dominate the noise for smaller separations and explain how to remove these additional noise effects in post-processing. We then combine PDI with angular differential imaging as a final layer of post-processing to further improve the contrast limits of our data at these separations. Results. For good observing conditions we achieve polarimetric contrast limits of 15.0–16.3 mag at the effective inner working angle of ~0.13′′, 16.3–18.3 mag at 0.5′′, and 18.8–20.4 mag at 1.5′′. The contrast limits closer in (≾0.6′′) display a significant dependence on observing conditions, while in the photon-noise-dominated regime (≿0.6′′) the limits mainly depend on the brightness of the star and the total integration time. We compare our results with contrast limits from other surveys and review the exoplanet detection limits obtained with different detection methods. For all our targets we achieve unprecedented contrast limits. Despite the high polarimetric contrasts we are not able to find any additional companions or extended polarised light sources in the data obtained so far.

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