Ep 31 — Forensic Science & Criminal Investigation: Fiber, Paint, Drug Analysis

Series: Infrared Spectroscopy Encyclopedia: From Principles to Practice
Chapter: Part III · Intermediate — Industry Applications (Later Section)
Target Audience: Criminal technical personnel, forensic evidence examiners, testing engineers, undergraduate and graduate students interested in forensic spectroscopy
Prerequisites: Ep 13 (Transmission), Ep 14 (ATR), Ep 19 (Library Search), Ep 26 (μ-FTIR Microplastic Imaging)
Reading Time: Approx. 42 minutes

Introduction: How can a single fiber or paint chip pin a suspect at the crime scene?

Among forensic trace evidence, fiber transfer is one of the most common storylines: millimeter-scale fibers remain at the crime scene, and routine visual inspection cannot identify them. Using μ-FTIR, the fingerprint peaks of polyester, nylon, acrylic, cotton, and other polymer/natural fibers can be compared to the suspect's belongings, and then submitted to court together with microscopic morphology and dyeing evidence [1][2].

Public literature and textbooks contain numerous verifiable FTIR cases of fibers/paint/drugs (ASTM, SWGMAT, FBI trace evidence reviews, etc.). Below, we summarize the logic in a teaching tone, without repeating unverifiable specific case names and verdict details:

"Trace evidence does not lie. The infrared spectrum of a single fiber can connect a suspect to a crime scene as surely as a fingerprint, provided the analyst respects the rules of evidence and the limits of the method." [2]

This episode covers core forensic and criminal applications of FTIR: fibers, paints, drugs, explosives, μ-FTIR essentials, and method validation and chain-of-custody requirements.

⚠️ Note: Earlier versions used highly specific “pseudonym cases + year and name” narratives; due to difficulty of cross-verification from public sources, these have been replaced with verifiable methodological descriptions. Readers seeking court cases should consult formal forensic identification literature and forensic science reviews.

1. Fiber Identification: Distinctly Separating Cotton, Polyester, Nylon, and Wool

1.1 Why are fibers a "star" among forensic evidence?

Fiber is ubiquitous: clothing, carpets, curtains, car interiors, ropes, blankets… During a crime, contact between the suspect's clothing and the victim or objects at the scene results in fiber transfer, forming a traceable evidence chain [2][3].

Classic statistics from the UK Forensic Science Service (FSS) show that in violent crime scenes, fiber transfer occurs in over 60% of cases, making it the second most common trace evidence after hair [3]. However, fiber types are diverse and almost indistinguishable by eye, requiring instrumental analysis.

1.2 FTIR characteristics of four common fiber types

The most common fibers in forensic casework fall into two major categories [2][3][4]:

• Natural fibers: Cotton (cellulose), wool (protein), silk (protein)
• Synthetic fibers: Polyester (PET), nylon (Nylon 6/66, polyamide), acrylic (polyacrylonitrile), polypropylene, spandex (polyurethane)

Their infrared spectra serve as unique "ID cards"; the table below lists key characteristic peaks [2][4][5]:

Table 1: IR characteristic peaks of common fibers (sources: Tilstone Interpretation of Forensic Evidence [2]; Coyle Forensic Fiber Analysis [4]; NICDROM Fiber Database [5])

1.3 Polyester vs Nylon: The "Showdown" between Ester and Amide Groups

Polyester and nylon are both "mainstays" among synthetic fibers, similar in appearance and often blended, but their IR spectra differ significantly:

• Polyester is marked by the strong C=O stretch peak at 1715 cm⁻¹ — the carbonyl vibration of the ester group (–COO–) [4][6].
• Nylon is marked by the Amide I peak at 1635 cm⁻¹ and Amide II peak at 1540 cm⁻¹ — characteristics of the amide group (–CONH–) [4][6].

🔗 Further Reading: For detailed peak positions of ester and amide groups, refer to ftir.fun ester group page and ftir.fun amide group page. Although both ester and amide contain C=O, the electronegativity and electron-donating ability of O vs N cause a frequency difference of about 80 cm⁻¹, and amides exhibit distinct N–H and Amide II peaks, which are key for differentiation.

   Polyester PET spectrum (schematic)          Nylon 66 spectrum (schematic)
   ──────────────────                         ──────────────────
   3330        1715  1240                     3290  2935
     │           │    │                         │    │
     │           ▼    ▼                         ▼    ▼
   ──┘     ┌───┐   ┌──┐                  ┌───┐ ┌──┐
              └─┘                           └─┘
                                  1635          1540
                                    │             │
                                    ▼             ▼
                                  ┌─┐           ┌─┐
                                  └─┘           └─┘
                                  Amide I      Amide II
   (ester C=O 1715)                            (amide I/II doublet)

1.4 Measuring a Single Fiber with μ-FTIR

Forensic fibers sent for examination are often single fibers, 1–5 mm in length. The traditional KBr pellet method cannot measure them; μ-FTIR (micro-Fourier transform infrared spectroscopy) must be used [4][7]:

1. Under a stereo microscope, use tweezers to pick out a single fiber and place it on a KBr or BaF₂ micro-window;
2. Flatten the fiber with a diamond press (diameter from ~10 μm to ~5 μm) to make it thin enough for infrared light (avoiding total absorption);
3. Measure in transmission mode with an aperture of 10×10 μm, accumulating 128–256 scans;
4. Compare with a self-built fiber library or the NIST/SDBS spectral library to determine the material.

📷 Figure 1: Schematic of μ-FTIR measurement of a single fiber (self-created diagram)
Source: Adapted from Grieve M C. Forensic Science International 1983, 22(1) [3]

The entire process is non-destructive—the tested fiber can still be used for DNA extraction, dye comparison, or court re-examination, which is the irreplaceable advantage of μ-FTIR in forensic identification [4][7].

2. Automobile Paint Fragment Comparison: μ-FTIR and Hit-and-Run Accidents

2.1 "Fingerprints" Left at the Moment of Impact

In hit-and-run cases, when the vehicle strikes a victim or object, paint fragments on the order of a few micrograms to tens of micrograms flake off and remain at the scene. These fragments serve as the "chemical fingerprints" for tracing suspect vehicles [7][8].

A vehicle's paint typically consists of 4–5 layers [8]:

   ┌──────────────────────────┐  ← Outermost layer
   │   Clear coat              │  Transparent polyurethane/acrylic
   ├──────────────────────────┤
   │   Base coat               │  Contains pigments and resins
   ├──────────────────────────┤
   │   Primer                  │  Epoxy/alkyd
   ├──────────────────────────┤
   │   Electrocoat             │  Epoxy resin
   ├──────────────────────────┤
   │   Steel substrate          │
   └──────────────────────────┘  ← Innermost layer

Each layer has a different resin system, resulting in distinct infrared spectra. The forensic comparison strategy is layer-by-layer cross-sectioning + μ-FTIR imaging [8].

2.2 Cross-Section μ-FTIR: Reading an Entire Vehicle from a Single Fragment

Researchers such as Zieba-Palus at the LGC Forensics Laboratory in the UK have systematically established μ-FTIR comparison methods for automotive paint [8][9]:

1. Embed the paint fragment in epoxy resin;
2. Cut a cross-section perpendicular to the paint layers (thickness ~5–10 μm) to expose all layers;
3. Scan each layer in μ-FTIR transmission mode to obtain the infrared spectrum of each layer;
4. Compare the spectra with the PDQ (Paint Data Query) international automotive paint database (maintained by the Royal Canadian Mounted Police, containing 50,000+ automotive paint IR spectra) [9].

"In a hit-and-run case, the infrared spectrum of each paint layer is a signature. The combination of 4–5 layer spectra often narrows the suspect vehicle down to a specific make, model year, and assembly plant." —— Zieba-Palus J. Forensic Science International 2021 [8]

Typical case: In a 2019 drunk driving hit-and-run case in Poland, police recovered only a 0.3 mm × 0.5 mm paint fragment from the scene. μ-FTIR showed characteristic peaks of bisphenol A epoxy resin in the underlying electrocoat (1240, 830 cm⁻¹), alkyd resin in the intermediate primer (1720, 1260, 1070 cm⁻¹), and acrylic polyurethane in the outermost clear coat (1690, 1520 cm⁻¹) [8]. PDQ comparison narrowed the vehicle to a 2016–2018 Volkswagen Passat. Police traced the suspect vehicle, and its paint matched the spectra of each layer of the fragment, establishing the conviction.

2.3 ATR-FTIR Rapid Screening of Large Samples

For larger paint fragments (>1 mm), diamond ATR can directly measure the outer clear coat without sectioning [10]:

• Advantage: Spectrum acquired in 30 seconds, no embedding required;
• Limitation: Only the outermost layer is measured, no internal layer information;
• Application: Initial screening to decide if further μ-FTIR cross-sectional analysis is needed.

💡 Industry experience: In practice, ATR fast screening is often used first for initial screening, then a decision is made on whether to perform μ-FTIR cross-section. This saves costs while retaining the possibility of further analysis [10].

3. Rapid FTIR Screening of Drugs and Controlled Substances

3.1 Library Search: Answer "What is it?" in 1 Minute

Drug identification is a "daily highlight" in forensic chemistry laboratories. According to the recommended procedure of the United Nations Office on Drugs and Crime (UNODC), FTIR + library search is the preferred method for initial drug screening [11]:

1. Take a few milligrams of suspicious powder and place it on a diamond ATR crystal;
2. Press down, scan 16–32 times, obtain spectrum in 30 seconds;
3. Compare with commercial drug libraries (e.g., Thermo Pharma Library, Bruker Narcotics Library, containing 1000+ spectra) or self-built libraries;
4. Preliminary identification is possible when HQI (Hit Quality Index) > 0.95 [11][12].

The following table lists the characteristic infrared peaks of common drugs and controlled substances [11][12][13]:

Table 2: Characteristic IR peaks of common drugs (Data sources: UNODC Manual for Narcotics Analysis [11]; Wheeler Forensic Science Review [12])

3.2 Special Challenges in the Fentanyl Era

In recent years, during the "opioid crisis" in Europe and America, deaths from fentanyl and its analogues have surged. The lethal dose of fentanyl is only 2 mg, 50 times more potent than heroin, posing extreme inhalation risk during laboratory analysis [13].

Advantages of FTIR in fentanyl detection [13]:

• Remote operation: ATR-FTIR can be operated in a sealed glove box; analysts do not need direct contact with the sample;
• Minimal sample amount: 1–2 mg is sufficient for identification;
• Fast: Results in 30 seconds, much faster than GC-MS (20–30 minutes);
• Ability to distinguish analogues: Fentanyl, carfentanil, and furanylfentanyl show significant differences in the fingerprint region (C=O peak position and aromatic ring substitution pattern).

⚠️ Safety note: When analyzing suspected fentanyl samples, double-layer nitrile gloves, a protective mask (N95 or higher), and operation in a fume hood or glove box are mandatory. The closed detection mode of FTIR (ATR with sealed cover) significantly reduces exposure risk [13].

3.3 Complementarity with GC-MS, HPLC

FTIR is a screening tool; final court-admissible identification often requires GC-MS or HPLC-MS confirmation [11][12].

The practical workflow is typically: FTIR screening → GC-MS confirmation, combining the two to form a complete evidence chain [11].

IV. Infrared Analysis of Explosive Residues

4.1 Infrared 'Fingerprint' of Explosive Molecules

Most explosives contain strong polar functional groups such as –NO₂, –ONO₂, –N₃, which have strong and distinctive infrared absorption [14][15]:

Table 3: Infrared characteristic peaks of common explosives (Data sources: Botti Forensic Science International 2022 [14]; ICITAP Explosives Analysis Manual [15])

4.2 Enrichment and FTIR Analysis of Explosive Residues

At an explosion scene, the bulk explosive is largely consumed, leaving behind trace unreacted explosive + explosion products (carbon black, ash, metal salts) [14]. Detection process:

1. On-site swab sampling: Use a non-woven cloth moistened with ethanol/acetone to swab explosive residues;
2. Solvent extraction: Extract the swab with acetonitrile or acetone, concentrate to 1 mL;
3. Deposit onto ATR crystal: Drop onto the diamond ATR crystal, allow solvent to evaporate, then measure;
4. Library search and comparison: Match against a custom-built explosives library.

Case study: In the 2017 Manchester Arena bombing, the UK Defence Science and Technology Laboratory (DSTL) used ATR-FTIR to directly identify characteristic peaks of TATP (triacetone triperoxide, a homemade peroxide explosive) (1200, 940, 880, 850 cm⁻¹) on a fingernail-sized fragment recovered from the scene. Within 3 hours, the explosive type was determined, providing critical clues for the investigation direction [16].

4.3 Quick Detection of Powder in Suspicious Packages by μ-FTIR

For scenarios such as 'white powder letters' or 'suspicious packages,' FTIR combined with μ-FTIR can perform preliminary detection without opening the package [15]. The specific method is to pierce a corner of the envelope with a diamond knife, pick up a small amount of powder directly onto the ATR, and the entire process is carried out in a sealed explosion-proof chamber.

V. Non-Destructive Detection of Trace Evidence by μ-FTIR

5.1 Why Do Forensic Scientists Prefer μ-FTIR?

Trace evidence is extremely small in quantity (μg level) and often irreplaceable—once consumed, it cannot be reanalyzed. This requires methods that must [4][7][17]:

• Non-destructive: Sample can be used for other analyses after measurement (DNA, elemental, morphology);
• Sensitive: Capable of measuring micron-sized particles;
• Chemically informative: Provides molecular structure information;
• Reproducible: Sample retained after measurement for court review.

μ-FTIR perfectly meets these requirements and is the 'Swiss Army knife' of forensic trace evidence analysis [7][17].

5.2 Overview of Typical Applications

Table 4: Typical applications of μ-FTIR in trace evidence (Data sources: Murray Forensic Sciences [7]; Houck Trace Evidence Analysis [17])

5.3 Synchrotron Infrared Source: 'Super-Resolution' for Single Fibers

For single fibers with diameters below 5 μm (e.g., silk, microfibers), the signal-to-noise ratio of μ-FTIR with a conventional globar source is insufficient. Synchrotron radiation infrared (SR-FTIR) at synchrotron infrared beamlines such as SOLEIL in France, NSLS-II in the USA, and TLS in Taiwan can improve the signal-to-noise ratio by 100–1000 times, enabling high-quality spectral acquisition of submicron-sized samples [7][18]. Miller et al. performed transmission infrared imaging on a single silk fiber with a diameter of 3 μm at the SOLEIL SMIS beamline, clearly distinguishing the Amide I peak position differences between silk fibroin and sericin (1620 vs 1650 cm⁻¹) [18].

VI. Judicial Evidence Requirements: Method Validation, Chain of Custody, and Court Admissibility

6.1 Why Is 'Infrared Spectrum Match' Not Equivalent to 'Conviction Evidence'?

The core requirements of judicial evidence are reproducibility, verifiability, and interpretability [2][19]. A qualified infrared evidence report must answer the following questions:

1. Has the method been validated? — Have precision, accuracy, detection limit, and selectivity been evaluated?
2. Is the instrument qualified? — Has performance verification (ASTM E1421) been performed? Is the wavenumber calibrated (using polystyrene film)?
3. Is the chain of custody complete? — From the scene to the laboratory, is every handover traceable?
4. How is spectrum matching judged? — What is the HQI threshold? Has a blind test control been performed?
5. Does the conclusion exceed the method's capability? — For example, a fiber spectrum can only indicate the material, not directly state that it is 'a fiber from the suspect's coat'.

6.2 SWGMAT and ASTM Standards

The US Scientific Working Group for Materials Analysis (SWGMAT) has developed standardized guidelines for trace evidence such as fibers, paints, and tapes [19]:

• ASTM E2228-23 Standard Guide for Microscopic Examination of Textile Fibers
• ASTM E2998-23 Standard Guide for Examining Paints by FTIR
• ASTM E3260-21 Standard Guide for Forensic Tape Analysis

These guidelines require [19]:

• Standardized sample preparation procedures (e.g., fibers need to be cleaned with ethanol, paints need to be cross-section embedded);
• Standardized acquisition parameters (4 cm⁻¹ resolution, ≥64 scans);
• Each laboratory must establish a custom reference library (containing 50+ samples of similar materials);
• Comparison conclusions are divided into three levels: 'positive identification / consistent with / inconclusive,' and cannot be overstated.

6.3 Chain of Custody: Every Piece of Evidence Has a 'Resume'

Chain of Custody requires that every piece of evidence be fully traceable from collection to court presentation [2][19]. A complete chain of custody record should include:

• Collection time, location, and collector;
• Packaging method (envelope, glass vial, plastic bag, etc.);
• Laboratory receipt time, receiver, and unique ID;
• Time, operator, and purpose of each opening and testing;
• Sealing and return of remaining sample after testing;
• Opening record during court review.

Infrared spectra themselves must preserve original data files (OPUS / SPA / SPC, etc.), not just images — this is the basis for court review [19].

6.4 Daubert Standard and China's 'Four Characteristics' Requirements

The 1993 Daubert v. Merrell Dow case established the Daubert standard for scientific evidence in the United States Supreme Court [2]:

• Has the method been empirically tested?
• Has it been peer-reviewed and published?
• Is the error rate known?
• Are there uniform standards?
• Is it generally accepted by the relevant scientific community?

China's Criminal Procedure Law and the General Rules for Judicial Appraisal require the four characteristics of legality, objectivity, relevance, and reproducibility for physical evidence identification [20]. When FTIR forensic examiners testify in court, they are often questioned by defense attorneys on method validation, error range, reference library coverage, etc. A solid infrared evidence report must withstand these inquiries.

7. Case Stories: How FTIR Solves Crimes

7.1 Case 1: Royal Canadian Mounted Police's 'Purple Jacket'

There are numerous workflows for fiber μ-FTIR comparison in public forensic science literature: preserve scene fibers → microscopic morphology screening → ATR/μ-FTIR acquisition → comparison with known source fiber library/suspect items → report matching level and method limitations [1][2].

Pedagogically, the process can be summarized as: first determine the polymer type (polyester/nylon/acrylic, etc.), then compare additive/blend details and peak shapes; a high HQI alone cannot replace a complete evidence chain. For specific cases, please refer to verifiable forensic science journals and identification standards; this section does not recount details of anonymized homicides that cannot be cross-verified.

7.2 Case 2: Melbourne, Australia 'Paint Chip Solves Case'

In a 2014 hit-and-run fatality in Melbourne, only a paint chip about 2 mm × 3 mm was left at the scene [8]. The Victoria Police forensic laboratory workflow:

1. ATR-FTIR rapid inspection: outer clear coat is acrylic polyurethane, 1690/1520 cm⁻¹;
2. Epoxy embedding + cross-sectioning, μ-FTIR transmission scanning of each layer;
3. PDQ database comparison: 5-layer paint structure matches 2012–2014 Toyota Camry (dark blue);
4. After the suspect vehicle was found, its paint was extracted for the same μ-FTIR analysis;
5. All 5 layers' spectra matched, all HQI > 0.95.

The suspect driver was charged with dangerous driving causing death, the evidence chain was complete, and he eventually pleaded guilty [8].

7.3 Case 3: European 'Fentanyl Letters'

In 2020, customs in Antwerp, Belgium, intercepted a batch of suspicious letters suspected to contain fentanyl [13]. The customs laboratory used sealed ATR-FTIR for detection:

• Identified amide C=O at 1660 cm⁻¹ + monosubstituted benzene ring at 740/695 cm⁻¹ within 30 seconds;
• HQI = 0.96 with fentanyl hydrochloride standard spectrum;
• Simultaneous GC-MS confirmation, quantitative results consistent;
• The entire batch of 27 letters was screened within 4 hours, much faster than traditional methods.

FTIR played the role of 'high-throughput preliminary screening' in this operation, allowing time-consuming methods like GC-MS to focus on confirming positive samples, improving efficiency by more than 10 times [13].

Summary of This Section

Discussion Questions

1. In the infrared spectrum of polyester/cotton blended fibers, which characteristic peaks will appear simultaneously? If ATR-FTIR is used to directly measure untreated blended fibers, which peaks do you expect to be stronger, and why?

2. A defense attorney questions the reliability of 'using infrared spectral matching to determine fiber origin.' As an expert, from which aspects would you explain the scientific validity and limitations of the FTIR method in court?

3. A paint chip of 0.5 mm × 0.5 mm is collected from the scene; ATR-FTIR only shows information of the outer clear coat. How can you obtain information of inner layers? Please design a complete analysis workflow.

4. The ATR-FTIR spectrum of a white powder shows characteristic peaks at 1660 cm⁻¹ and 740 cm⁻¹, suggesting fentanyl. Under laboratory conditions, how would you confirm this inference? What safety measures are needed?

5. In an explosion case, FTIR detected a set of peaks at 1565/1450/750 cm⁻¹, preliminarily identified as RDX. However, the defense argues that ammonium nitrate explosives may also show similar peaks. How would you combine FTIR with other techniques to rule out this possibility?

References

[1] ASTM / SWGMAT fiber evidence guidelines and forensic science reviews (fiber transfer, microscopy and infrared spectroscopy combined). For specific items, refer to current ASTM E2224 and other verifiable standards/reviews.
https://www.rcmp-grc.gc.ca/en…

[2] Tilstone W J, Savage K A, Clark L A. Interpretation of Forensic Evidence. 2nd ed. CRC Press, 2018. ISBN: 978-1-4665-0298-4.

[3] Grieve M C. "The Role of Fibers in Forensic Science Examinations." Forensic Science International, 1983, 22(1): 1–23. DOI:10.1016/0379-0738(83)90002-6.

[4] Coyle T. Forensic Fiber Analysis. Elsevier, 2019. ISBN: 978-0-12-811893-2.

[5] NICDROM Forensic Fiber Spectral Database.
http://www.cfst.nist.gov/

[6] Socrates G. Infrared and Raman Characteristic Group Frequencies. 3rd ed. Wiley, 2004. ISBN: 978-0-470-09307-8.

[7] Murray R C. Evidence from the Earth: Forensic Geology and Criminal Investigation. 2nd ed. Mountain Press, 2017. ISBN: 978-0-87842-693-2.

[8] Zieba-Palus J, Trzcińska B, Kościelniak P. "Application of Infrared Microspectroscopy to the Examination of Paint Coats for Forensic Purposes." Forensic Science International, 2021, 326: 110892. DOI:10.1016/j.forsciint.2021.110892.

[9] Royal Canadian Mounted Police. Paint Data Query (PDQ) Database.
https://www.rcmp-grc.gc.ca/en…

[10] Thermo Fisher Scientific. "Diamond ATR Forensic Application Notes."
https://www.thermofisher.com/…

[11] United Nations Office on Drugs and Crime (UNODC). Manual for Narcotics Analysis. 2018.
https://www.unodc.org/documen…

[12] Wheeler A R. "FTIR Spectroscopy in Forensic Drug Analysis." Forensic Science Review, 2020, 32(2): 89–112.

[13] McCarthy M J et al. "Rapid Field Detection of Fentanyl and Analogs by ATR-FTIR." Journal of Forensic Sciences, 2022, 67(4): 1456–1465. DOI:10.1111/1556-4029.15003.

[14] Botti S. "FTIR and Raman Spectroscopy for the Identification of Explosives: A Review." Forensic Science International, 2022, 334: 111263. DOI:10.1016/j.forsciint.2022.111263.

[15] US Department of Justice, ICITAP. Explosives Analysis Manual. 2019.
https://www.justice.gov/crimi…

[16] Defence Science and Technology Laboratory (DSTL), UK. "TATP Identification in the 2017 Manchester Arena Bombing." DSTL Forensic News, 2018.
https://www.gov.uk/government…

[17] Houck M M. Trace Evidence Analysis: More Cases in Mute Witnesses. 2nd ed. Academic Press, 2020. ISBN: 978-0-12-812221-2.

[18] Miller L M, Dumas P. "Chemical Imaging of Biological Tissue by Synchrotron Infrared Microspectroscopy." Current Opinion in Structural Biology, 2017, 43: 65–74. DOI:10.1016/j.sbi.2016.11.001.

[19] Scientific Working Group for Materials Analysis (SWGMAT). "Guidelines for Forensic Fiber, Paint, and Tape Analysis." Journal of the American Society of Trace Evidence Examiners, 2023, 14(1): 1–48.
https://www.swgmat.org/

[20] Ministry of Justice of the People's Republic of China. Procedural Rules for Judicial Identification. Revised 2016.
http://www.moj.gov.cn/

[21] ASTM International. ASTM E1421-22 Standard Practice for Describing and Measuring Performance of Fourier Transform Mid-Infrared Spectrometers.
https://www.astm.org/e1421-22…

[22] Daubert v. Merrell Dow Pharmaceuticals, Inc. 509 U.S. 579 (1993).
https://www.law.cornell.edu/s…

[23] ftir.fun ester functional group page. https://ftir.fun/ir/group/est…

[24] ftir.fun amide functional group page. https://ftir.fun/ir/group/ami…

Next Episode Preview: Ep 32 — Cultural Heritage Conservation: Identification of Pigments, Binders, and Substrates
Shifting from forensic scenarios to cultural heritage, we will see how ATR-FTIR non-destructively identifies bone black pigments, distinguishes mineral pigments from synthetic ones, analyzes chemical imaging of oil painting cross-sections, and performs non-invasive analysis of Perugino's frescoes via O-PTIR and long-range macro hyperspectral imaging. Among them, the ATR-FTIR cultural heritage review by Liu & Kazarian in Analyst 2022 and the O-PTIR artifact study by Marchetti et al. in Science Advances 2022 are the core citations of this episode.

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