28
H. Kaur et al.
amide I (~1635 cm
−1 ), amide II (~1531 cm
−1 ) and amide III (~1238 and ~1304 cm
−1 )
vibrational modes from the peptide chains, respectively. The vibration pattern from
the C–O bond and the bending mode of C–O–H vibration is projected at 1082 and
1165 cm
−1 respectively. Other peaks including O–H stretch mode (~3278 cm
−1 ) and
alkyl stretch modes (~2872, 2931, 2958 cm
−1 ) were also noted. Sample aging is
observed by calculating the peak IR absorbance ratios of 1531 and 1635 cm
−1 peak
positions which tends to increase as the sample ages from 1/4th—1 day, and then
gets equilibrated after the first day. Likewise, the vibrational spectra of human semen
samples (Fig. 15, panel b) were evaluated at different time rates, i.e., fresh sample,
sample after 5/4th day, 5, and 30 days, and approximately similar peak positions
were observed on comparing with the blood samples. Both the samples displayed
approximately similar peak patterns considering the contribution from the protein
albumin that is an intrinsic part of both. However, contrasting to the blood sample
spectra, semen samples show an appearance of the 1057 cm
−1 peak position assigned
to the asymmetric mode of P–O–C vibration. For the human semen sample examination at different times, the IR intensity ratios of the peaks at position 1240 and
1633 cm
−1 were considered which reduced in its intensity as the sample ages, indicating the degradation of the sample components. Fresh samples were dominated
by the broad water absorbance peaks since they were evaluated in the liquid state.
While using the ATR technique to distinguish between the two biofluids (Fig. 15,
panel a and b), the fresh blood sample retained a 1531 cm
−1 peak which is absent
from the fresh semen sample spectra. Further, the vibration mode from C–O stretch
and C–O–H bending mode is observed for blood samples while asymmetric P–O–C
vibration mode is distinctive for the human semen samples. This work established the
basis of the combination of ATR-FTIR mid-infrared radiation-based technique and
Raman spectroscopy to carry out a chemical-free evaluation of the on-scene procured
samples depending on their degradative timeline. This could affirm in correlating the
suspected individuals with crime events.
Mamede et al. [80] estimated the compositional changes and identification of the
type of bone from the perspective of the archeological forensics of the burned bone
samples. Utilizing the vibrational spectroscopic tools, the authors studied the role
of OH vibration modes in spectroscopically establishing a distinction between the
archeological remains of recently burned and ancient burned fossils of bones and
teeth (Fig. 16). Platinum single-crystal ATR assembly was utilized in this study.
Both the sets presented sharp phosphate signatures (603 and 1035 cm
−1 ) that are
indicative of their high crystalline property (Fig. 16, panel a, b and c). However, a
distinction among the two sets arises in observing the OH stretch contribution (at
~3572 cm
−1 ) and OH liberation peak (~630 cm
−1 ) from the recent skeletal remains
(Fig. 16, panel d and e) instead of the fossil samples (panel a) which is very less.
From the ATR spectra, OH/P ratio values were considered as a landmark to analyze
the burned bone or teeth samples. From the observed spectral features, it is inferred
that the mineralization of the fossil bone matrix leads to the replacement of the
hydroxyl groups with different anions with time. This crystallinity pattern of the
recently burned and fossilized samples differs and the occurrence or absence of the
OH mode in the vibrational spectra is an indication of their discrimination.
H. Kaur et al.
amide I (~1635 cm
−1 ), amide II (~1531 cm
−1 ) and amide III (~1238 and ~1304 cm
−1 )
vibrational modes from the peptide chains, respectively. The vibration pattern from
the C–O bond and the bending mode of C–O–H vibration is projected at 1082 and
1165 cm
−1 respectively. Other peaks including O–H stretch mode (~3278 cm
−1 ) and
alkyl stretch modes (~2872, 2931, 2958 cm
−1 ) were also noted. Sample aging is
observed by calculating the peak IR absorbance ratios of 1531 and 1635 cm
−1 peak
positions which tends to increase as the sample ages from 1/4th—1 day, and then
gets equilibrated after the first day. Likewise, the vibrational spectra of human semen
samples (Fig. 15, panel b) were evaluated at different time rates, i.e., fresh sample,
sample after 5/4th day, 5, and 30 days, and approximately similar peak positions
were observed on comparing with the blood samples. Both the samples displayed
approximately similar peak patterns considering the contribution from the protein
albumin that is an intrinsic part of both. However, contrasting to the blood sample
spectra, semen samples show an appearance of the 1057 cm
−1 peak position assigned
to the asymmetric mode of P–O–C vibration. For the human semen sample examination at different times, the IR intensity ratios of the peaks at position 1240 and
1633 cm
−1 were considered which reduced in its intensity as the sample ages, indicating the degradation of the sample components. Fresh samples were dominated
by the broad water absorbance peaks since they were evaluated in the liquid state.
While using the ATR technique to distinguish between the two biofluids (Fig. 15,
panel a and b), the fresh blood sample retained a 1531 cm
−1 peak which is absent
from the fresh semen sample spectra. Further, the vibration mode from C–O stretch
and C–O–H bending mode is observed for blood samples while asymmetric P–O–C
vibration mode is distinctive for the human semen samples. This work established the
basis of the combination of ATR-FTIR mid-infrared radiation-based technique and
Raman spectroscopy to carry out a chemical-free evaluation of the on-scene procured
samples depending on their degradative timeline. This could affirm in correlating the
suspected individuals with crime events.
Mamede et al. [80] estimated the compositional changes and identification of the
type of bone from the perspective of the archeological forensics of the burned bone
samples. Utilizing the vibrational spectroscopic tools, the authors studied the role
of OH vibration modes in spectroscopically establishing a distinction between the
archeological remains of recently burned and ancient burned fossils of bones and
teeth (Fig. 16). Platinum single-crystal ATR assembly was utilized in this study.
Both the sets presented sharp phosphate signatures (603 and 1035 cm
−1 ) that are
indicative of their high crystalline property (Fig. 16, panel a, b and c). However, a
distinction among the two sets arises in observing the OH stretch contribution (at
~3572 cm
−1 ) and OH liberation peak (~630 cm
−1 ) from the recent skeletal remains
(Fig. 16, panel d and e) instead of the fossil samples (panel a) which is very less.
From the ATR spectra, OH/P ratio values were considered as a landmark to analyze
the burned bone or teeth samples. From the observed spectral features, it is inferred
that the mineralization of the fossil bone matrix leads to the replacement of the
hydroxyl groups with different anions with time. This crystallinity pattern of the
recently burned and fossilized samples differs and the occurrence or absence of the
OH mode in the vibrational spectra is an indication of their discrimination.