Overview of Raman Spectroscopy: Fundamental to Applications
167
(MCR-ALS) to show the order of crossed lines drawn and by utilizing confocal
Raman spectroscopic imaging obliteration in writing samples [176]. Recently, Zi˛ ebaPalus and the group examined the causes responsible for paper degradation and
their ageing [177]. Further, Gorshkova et al. used the method of spectral analysis
to determine the age of the writing inks, and in this process found that the narrow
section of Raman spectra contains characteristic lines and the analysis of this narrow
section using PCA chemometric approach enabled the separation of writing inks into
groups (clusters) corresponding to different creation interval [178]. Ultimately, it is
evident that Raman spectroscopy can be used to investigate several specific features
relating to the study of questioned documents for forensic casework records.
4.3.3 Identification of Drugs of Abuse
The widespread use of illicit drugs within contemporary society is an unprecedented
global crisis in human history. Certain drugs (e.g., cocaine) are closely associated
with a rise in crime and abuse. Moreover, the widespread use of illegal drugs poses
a serious threat to the protection and welfare of humanity, public health particularly youth; as well as to the safety and sovereignty of countries [179]. Lednev
group and Khandasammy et al. have presented comprehensive reviews on applications of Raman spectroscopy in the detection and estimation of cocaine and other
illegal drugs of abuse [180, 181]. Silveira and the group observed that Raman spectroscopy (near-IR) may be utilized to differentiate the various types of cocaine (crack
cocaine, cocaine hydrochloride powder, freebase powder, and paste) [182]. Penido
et al. combined the FT-IR spectroscopy with the utility of Raman spectroscopy to
quantify cocaine in ternary mixtures in another piece of work [183]. Investigators
noticed that Raman spectroscopy could be utilized in combination with PLS regression models to estimate the quantity of cocaine in the samples, even at low content
of cocaine (as low as 30%) [183]. Jones et al. have used a combined approach of
IR and Raman spectroscopy and reported that 76% of the 221 psychoactive drugs
they analyzed could be correctly classified after expanding the instruments’ libraries
[184]. Rebiere and colleagues used Raman spectroscopy in combination with nearIR spectroscopy to examine eight specimens of anabolic drugs, which are illegally
utilized by several athletes for performance-enhancing purposes [185]. Some of the
samples they found were containing steroids and many of the remaining ingredients
listed were lactose, talc, starch, and sucrose [185]. In the last few years, researchers
have been working on developing small, portable Raman spectrometers that can be
taken to the crime scenes. Ali and group illustrated the capability of portable Raman
spectrometers to recognize flunitrazepam, known as a date rape drug also recognized
as Rohypnol or “roofies”, in different spiked alcoholic drinks at low concentrations
such as 0.01% and for that, no sample extraction required [186]. The use of surfaceenhanced Raman spectroscopy (SERS) and the evolution of new SERS substrates is
a major subject of extensive studies in recent years investigating drug analysis and
tracking. The comprehensive details of the fundamentals and working of SERS are
discussed in the next chapter. Most recently, the Fu group using commercial SERS
167
(MCR-ALS) to show the order of crossed lines drawn and by utilizing confocal
Raman spectroscopic imaging obliteration in writing samples [176]. Recently, Zi˛ ebaPalus and the group examined the causes responsible for paper degradation and
their ageing [177]. Further, Gorshkova et al. used the method of spectral analysis
to determine the age of the writing inks, and in this process found that the narrow
section of Raman spectra contains characteristic lines and the analysis of this narrow
section using PCA chemometric approach enabled the separation of writing inks into
groups (clusters) corresponding to different creation interval [178]. Ultimately, it is
evident that Raman spectroscopy can be used to investigate several specific features
relating to the study of questioned documents for forensic casework records.
4.3.3 Identification of Drugs of Abuse
The widespread use of illicit drugs within contemporary society is an unprecedented
global crisis in human history. Certain drugs (e.g., cocaine) are closely associated
with a rise in crime and abuse. Moreover, the widespread use of illegal drugs poses
a serious threat to the protection and welfare of humanity, public health particularly youth; as well as to the safety and sovereignty of countries [179]. Lednev
group and Khandasammy et al. have presented comprehensive reviews on applications of Raman spectroscopy in the detection and estimation of cocaine and other
illegal drugs of abuse [180, 181]. Silveira and the group observed that Raman spectroscopy (near-IR) may be utilized to differentiate the various types of cocaine (crack
cocaine, cocaine hydrochloride powder, freebase powder, and paste) [182]. Penido
et al. combined the FT-IR spectroscopy with the utility of Raman spectroscopy to
quantify cocaine in ternary mixtures in another piece of work [183]. Investigators
noticed that Raman spectroscopy could be utilized in combination with PLS regression models to estimate the quantity of cocaine in the samples, even at low content
of cocaine (as low as 30%) [183]. Jones et al. have used a combined approach of
IR and Raman spectroscopy and reported that 76% of the 221 psychoactive drugs
they analyzed could be correctly classified after expanding the instruments’ libraries
[184]. Rebiere and colleagues used Raman spectroscopy in combination with nearIR spectroscopy to examine eight specimens of anabolic drugs, which are illegally
utilized by several athletes for performance-enhancing purposes [185]. Some of the
samples they found were containing steroids and many of the remaining ingredients
listed were lactose, talc, starch, and sucrose [185]. In the last few years, researchers
have been working on developing small, portable Raman spectrometers that can be
taken to the crime scenes. Ali and group illustrated the capability of portable Raman
spectrometers to recognize flunitrazepam, known as a date rape drug also recognized
as Rohypnol or “roofies”, in different spiked alcoholic drinks at low concentrations
such as 0.01% and for that, no sample extraction required [186]. The use of surfaceenhanced Raman spectroscopy (SERS) and the evolution of new SERS substrates is
a major subject of extensive studies in recent years investigating drug analysis and
tracking. The comprehensive details of the fundamentals and working of SERS are
discussed in the next chapter. Most recently, the Fu group using commercial SERS