Classical- and Heterodyne-Detected Vibrational Sum …
107
Fig. 9 Imχ (2) spectra of air-water interface in presence of a DMSO b acetone and c propylene
carbonate (PC). The spectrum of the neat air-water interface (black curve) is shown in each panel
for comparison. The bulk concentration of each amphiphile is 1.5 M. Adapted with permission
from [33]. Copyright 2020 Anita Publications
methyl-up orientation [4] which is in agreement with the hydrophobic nature of
methyl group.
Perturbing influence of the amphiphiles (on interfacial water) increases with
increasing their hydrophobicity, DMSO < acetone < PC. At air-water-DMSO interface, the OH stretch band shape (3000–3600 cm
−1 ) is quite similar to that of the
neat air-water interface, but the amplitude is marginally decreased. With acetone, the
reduction of the amplitude (3000–3600 cm
−1 ) becomes more noticeable, suggesting
increased alteration of the net orientation of interfacial water in presence of acetone.
For PC which has the larger alkyl group as well as more number of ‘O’ atoms, the
effect is even more substantial with the appearance of a distinct positive band around
3200 cm
−1 and subsequent reduction in amplitude around 3450 cm
−1 . The change
in the OH stretch band clearly suggests that the interfacial water increasingly adopts
a net H-up orientation in the presence of PC. Compared to DMSO and acetone, PC
possesses two additional ‘O’ atoms that are H-bond acceptor. The interfacial water
hydrating such O-atom via H-bond donation may adopt a preferential H-up orientation. Moreover, the differential distribution of the amphiphiles across the interface
contributes to the net orientation of the interfacial water [33].
5.4 Perfluorinated Persistent Organic Pollutant (POP)
at Environmentally Relevant Aqueous Interfaces
Unlike degradable pollutants which have a short-term effect on the environment,
persistent organic pollutants (POPs), because of their resistance to degradation, have
a long-term effect on aqueous interface and the associated biotic/abiotic systems.
107
Fig. 9 Imχ (2) spectra of air-water interface in presence of a DMSO b acetone and c propylene
carbonate (PC). The spectrum of the neat air-water interface (black curve) is shown in each panel
for comparison. The bulk concentration of each amphiphile is 1.5 M. Adapted with permission
from [33]. Copyright 2020 Anita Publications
methyl-up orientation [4] which is in agreement with the hydrophobic nature of
methyl group.
Perturbing influence of the amphiphiles (on interfacial water) increases with
increasing their hydrophobicity, DMSO < acetone < PC. At air-water-DMSO interface, the OH stretch band shape (3000–3600 cm
−1 ) is quite similar to that of the
neat air-water interface, but the amplitude is marginally decreased. With acetone, the
reduction of the amplitude (3000–3600 cm
−1 ) becomes more noticeable, suggesting
increased alteration of the net orientation of interfacial water in presence of acetone.
For PC which has the larger alkyl group as well as more number of ‘O’ atoms, the
effect is even more substantial with the appearance of a distinct positive band around
3200 cm
−1 and subsequent reduction in amplitude around 3450 cm
−1 . The change
in the OH stretch band clearly suggests that the interfacial water increasingly adopts
a net H-up orientation in the presence of PC. Compared to DMSO and acetone, PC
possesses two additional ‘O’ atoms that are H-bond acceptor. The interfacial water
hydrating such O-atom via H-bond donation may adopt a preferential H-up orientation. Moreover, the differential distribution of the amphiphiles across the interface
contributes to the net orientation of the interfacial water [33].
5.4 Perfluorinated Persistent Organic Pollutant (POP)
at Environmentally Relevant Aqueous Interfaces
Unlike degradable pollutants which have a short-term effect on the environment,
persistent organic pollutants (POPs), because of their resistance to degradation, have
a long-term effect on aqueous interface and the associated biotic/abiotic systems.