Tellus X-Ray Diffractometer in Forensic Applications

LINEV Systems introduces the next-generation benchtop X-ray diffractometer TELLUS Pro, offering enhanced capabilities and designed to meet the needs of cutting-edge analysis. The instrument is the only diffractometer that combines the compact design with the high X-ray source power (1.2 kW) and large goniometer radius (up to 210 mm). These features ensure the increased resolution and sensitivity, which are of great importance for precise and reliable forensic analysis.

X-ray diffractometry (XRD) is a non-destructive technique used to determine the crystal properties of a sample under investigation by analyzing the angular distribution of the reflected X-ray emission intensity. The crystal properties of a substance can be regarded as its unique “fingerprint,” which makes it possible to distinguish and identify the phase content of unknown mixtures of solids.

Strictly speaking, XRD can only be applied to the direct investigation of crystalline substances in which atoms are arranged in a periodically repeating structure. On the other hand, most (>90%) of the solids in the world, whether of natural or artificial origin, are crystalline (including metals, rocks, building materials, medicines, and many other materials), which ensures the exceptionally high applicability of XRD in various kinds of investigations. This fact led to the widespread use of XRD in forensic analysis for decades.

Although the real range of possible samples for testing in forensic analysis is practically unlimited, one can outline the following main areas:

– Soils and building materials (cement, mortar, concrete, etc.) investigations and comparisons are carried out to establish a possible relation between a crime scene and evidence remaining in shoe soles, car tires, etc.

– Explosives and post-blast residues analysis is used both for tests of potentially dangerous cargo and clarification of the explosion circumstances.

– Pigments and paints analysis comprises verification of the artwork’s authenticity and identification of vehicle paint after traffic accidents.

– Analysis of drugs and substances that can potentially contain psychotropic substances.

– Confirmation of the presence of a relic of bones after a fire or other damaging factors.

– Comparison of textile fibers to distinguish between them.

– Identification of any unknown substances and mixtures which can potentially contain dangerous fractions (poison, contaminants, etc.).

It should be noted that XRD, in contrast to chemical and elemental analysis, can distinguish polymorphs (i.e., materials having the same chemical formula but different crystallographic structures). This ability is an essential factor while trying to find slight differences in similar samples of soil and building materials. This capability that neither spectroscopic nor chromatographic methods can fully replicate. XRD is invaluable in forensic science for its ability to non-destructively identify and quantify crystalline phases in trace evidence, turning microscopic particles into definitive links between suspects, victims, and crime scenes.

A common feature of almost all forensic analysis applications is a limited amount of sample for investigation, which demands that analytical instruments have high sensitivity and provide low parasitic signal. For this reason, X-Ray diffractometers for forensic applications should have sufficiently high emission source power and detector sensitivity as well as it should provide the maximal possible signal-to-noise and signal-to-background ratios.

TELLUS Pro diffractometer

The new diffractometer model TELLUS Pro from LINEV Systems is a benchtop XRD tool built around a θ/θ Bragg–Brentano geometry. It features a high-precision goniometer and a state-of-the-art high sensitive photon counting array detector providing superior angular resolution and reproducibility for routine sample screening in forensic laboratories. The vertical goniometer provides a stable horizontal orientation for powder or liquid-like samples while eliminating spillover risks.

The substances search is performed over high volume crystallographic databases (COD, PDF) containing several hundred thousand entries.

The diffractometer has a compact design with a relatively small footprint, but its superior performances expand its capabilities beyond those of “conventional” benchtop powder XRD systems. First, the increased X-Ray source power of 1.2 kW provides nearly twice the intensity compared to most other commercial benchtop diffractometers which is essential for investigation of extremely small samples. Second, the goniometer radius of the TELLUS Pro can be varied from 150 to 210 mm, which provides flexibility in achieving an acceptable trade-off between resolution and signal intensity. The increased goniometer radius makes it possible to achieve the measured diffraction peaks full width at half maximum (FWHM) value to be less than 0.03° which is rare for benchtop diffractometers. It should be noted, that the low FWHM (i.e. high resolution) is critical for forensic investigation as it can help to detect a slight difference in similar soil samples (e. g., in cases where several samples are taken at different but closely spaced locations).

Besides XRD measurements themselves, another key point of any successful investigation is smart and efficient analytical software that transforms raw diffraction patterns into actionable forensic intelligence by automating phase identification, quantification, structural refinement, statistical comparison, and comprehensive reporting, which are essential steps for linking trace evidence to crime scenes. All this functionality is covered by ALMAZ software from LINEV Systems. The substances search is performed over high volume crystallographic databases (COD, PDF) containing several hundred thousand entries.

TELLUS Pro advanced radiation protection creates a secure working environment for all operators. The diffractometer features reliable stationary X-ray shielding combined with a multi-level electronic security system, effectively eliminating direct radiation exposure. The automatic safety system is designed with multiple layers of protection.

Application examples

XRD is a powerful tool in textile identification, helping to distinguish between different fiber types and even within the same type based on the unique structures of the textile and pigments. This technique is beneficial in forensic science because it can analyze small samples and minute traces of fibers, which are often found at crime scenes. If no any reference sample for comparison is available, then a measured diffractogram of a sample under investigation can be compared with a pre-prepared database of known fiber patterns.

In the figure, an example of XRD measurements is shown, which demonstrates the possibility of determining the source of a small fragment of a textile fiber. One can observe similarities in the diffractograms of the small fragment and the sample Textile #2. To minimize the impact of background signal originating from parasitic scattered X-Ray emission, a monocrystal zero-background cuvette should be used to measure small samples.

Persistent threats posed by terrorist organizations and criminals drive the need for improved explosive detection and analysis. Even relatively small amounts for explosives lead to significant risk to life and infrastructure, making rapid and reliable identification methods essential. Beyond detecting the primary explosive, XRD can quantify minor crystalline phases (synthesis byproducts, stabilizers, or even amorphous binders) down to a few percent of a sample. It helps trace an explosive sample back to its manufacturing route and determine its origin.

In the figure, X-Ray pattern of a fireworks filler is shown together with qualitative and quantitative content analysis results, which demonstrate the presence of explosives.