Examination of Firearms Review: 2007 to 2010 - Interpol

2.3.2 Raman spectroscopy
Raman spectroscopy uses near infrared light for excitation. Although this technique
requires sample preparation (the required amount can be as low as picograms or
femtoliters), the sample (e.g. swab) can still be used for laboratory DNA testing. The
result of Raman spectroscopy is a Raman spectrum (Figure 2), which provides a
vibrational signature of the sampled material. A portable Raman spectrometer is
already available 3 .
Figure
2.
Raman
spectra,
with
785‐nm
excitation
(by
Virkler
and
Lednev 2 )
2.3.3 XRF
Besides fluorescence spectroscopy and Raman spectroscopy, X-ray fluorescence
(XRF) is a presumptive test worth mentioning. Originally XRF was designed for
elemental analysis during planetary exploration, though it can also be used to detect
blood due to the presence of iron in haemoglobin, and semen due to the presence of
zinc. This technique is particularly valuable because it is non-destructive compared to
other screening techniques.
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