162
D. K. Pandey et al.
Adding the water to ILs greatly changes the cation–anion interactions and modifies
the related physicochemical properties such as viscosity, polarity, electrical conductivity for various applications [106, 107]. Therefore, we must gain a better understanding of the interactions between the ILs and water molecules. Extensive studies
were done by researchers using Raman spectroscopic techniques to study HB interactions and conformation equilibria [103, 109–111]. In this regard, our group recently
examined the impact of water on the C 2 mim X ILs, where all the ILs identified in
gauche conformation, and also reported the weakening of the interaction between
ion-pair due to the interaction with water molecules [112, 113]. The C 4/5 -H Raman
bands greatly blue-shifted by +33, +41, and +42 cm
−1 going from neat ILs having
Cl, Br, and I anions to the corresponding water mixtures, respectively, indicates
weakening of ion-pair interaction [113]. In a water-rich environment, the change
in relative intensities of Raman bands at ~2946 and ~2950 cm
−1 corresponding to
ν s (CH 2 ) and ν as (CH 3 ), respectively, confirm the conformational change of the alkyl
chain [113]. Since this area is so vast that we cannot list all the studies and aspects
here, these review articles can be very useful for interested readers from which they
can obtain more basic knowledge of these interesting materials and their applications
[114–116].
4.2 Material Science
In material science, Raman spectroscopy emerges as privileged research equipment
that offers a characterization of a diverse and demanding selection of specimens from
carbonaceous materials to Archaeological materials. This technique is extremely
applicable as an important method of characterization to many classes of materials
due to its fast and non-destructive nature. Thus, this segment discusses the immense
signature applications of Raman spectroscopy in various material science fields.
4.2.1 Carbonaceous Materials.
Natural carbon demonstrates its unique characteristics and novel properties such
as tremendous mechanical strength, range of conductivity in different phases and
dimensions. The Raman spectroscopy is being a versatile tool for understanding
the change in structure and vibrational properties. Ferrari et al. have recorded the
Raman spectra of graphene (defect-free) and bulk graphite shown in Fig. 7a, which
clearly differentiate both the structures [117]. Also, the G peaks slightly shifted to
low wavenumbers. Figure 7b shows that the D peak is changed in shape, width,
and position as the number of layers increases [117]. Figure 7c reveals the disorderinduced Raman spectra of graphene portray an additional D and D’ peak at 1350
and 1620 cm
−1 , respectively, where the D band is located at half of the position of
the 2D peaks [118]. Sahoo et al. evaluated the field-emission properties of reduced
graphene oxide (rGO) by studying the in-situ Raman spectra [119]. Figure 7d shows
D. K. Pandey et al.
Adding the water to ILs greatly changes the cation–anion interactions and modifies
the related physicochemical properties such as viscosity, polarity, electrical conductivity for various applications [106, 107]. Therefore, we must gain a better understanding of the interactions between the ILs and water molecules. Extensive studies
were done by researchers using Raman spectroscopic techniques to study HB interactions and conformation equilibria [103, 109–111]. In this regard, our group recently
examined the impact of water on the C 2 mim X ILs, where all the ILs identified in
gauche conformation, and also reported the weakening of the interaction between
ion-pair due to the interaction with water molecules [112, 113]. The C 4/5 -H Raman
bands greatly blue-shifted by +33, +41, and +42 cm
−1 going from neat ILs having
Cl, Br, and I anions to the corresponding water mixtures, respectively, indicates
weakening of ion-pair interaction [113]. In a water-rich environment, the change
in relative intensities of Raman bands at ~2946 and ~2950 cm
−1 corresponding to
ν s (CH 2 ) and ν as (CH 3 ), respectively, confirm the conformational change of the alkyl
chain [113]. Since this area is so vast that we cannot list all the studies and aspects
here, these review articles can be very useful for interested readers from which they
can obtain more basic knowledge of these interesting materials and their applications
[114–116].
4.2 Material Science
In material science, Raman spectroscopy emerges as privileged research equipment
that offers a characterization of a diverse and demanding selection of specimens from
carbonaceous materials to Archaeological materials. This technique is extremely
applicable as an important method of characterization to many classes of materials
due to its fast and non-destructive nature. Thus, this segment discusses the immense
signature applications of Raman spectroscopy in various material science fields.
4.2.1 Carbonaceous Materials.
Natural carbon demonstrates its unique characteristics and novel properties such
as tremendous mechanical strength, range of conductivity in different phases and
dimensions. The Raman spectroscopy is being a versatile tool for understanding
the change in structure and vibrational properties. Ferrari et al. have recorded the
Raman spectra of graphene (defect-free) and bulk graphite shown in Fig. 7a, which
clearly differentiate both the structures [117]. Also, the G peaks slightly shifted to
low wavenumbers. Figure 7b shows that the D peak is changed in shape, width,
and position as the number of layers increases [117]. Figure 7c reveals the disorderinduced Raman spectra of graphene portray an additional D and D’ peak at 1350
and 1620 cm
−1 , respectively, where the D band is located at half of the position of
the 2D peaks [118]. Sahoo et al. evaluated the field-emission properties of reduced
graphene oxide (rGO) by studying the in-situ Raman spectra [119]. Figure 7d shows