1. PhD Chemistry (Analytical) Area of Research Interest:
Muhammad Mushtaq
PhD Chemistry (Analytical)
Area of Research Interest:
Hplc-based METHOD development and validation,
revalorization of under-utilized agricultural-waste streams into phenolics of high antioxidant potential
Development of highly sensitive and selective molecule counting machines
Teaching Interests: Analytical Chemistry,
Physical Chemistry
Title of talk: Vibrational changes during water dynamics: AN evitable and non-destructive diagnostic tool

2. Water: Universal solvent and main absorber
Background:
Water: A Universal solvent and main absorber of sunlight
Quickly absorbs in UV, Visible, Infrared and Microwave
Water molecule may vibrate in number of ways (very complex and phase dependent)
IR frequencies change with intermolecular integrity
Non-destructive profiling with zero or little sample preparation
More suitable for living organisms

3. Fundamental vibrations in water
ν1,O-H symmetric stretching 3657 cm−1        
ν2, H-O-H bending 1595 cm−1                                     
ν3, O-H asymmetric stretching 3756 cm−1
In the gas phase all three bands show
extensive rotational fine structure
There is no rotational in liquid and solid but the absorption bands are broader
because of hydrogen bonding
a 3rd overtone falls visible region
(responsible for blue color of water)
IR cuvettes made of substances which are water-insoluble (calcium fluoride).
This difficulty has been overwhelmed by an attenuated total reflectance (ATR)
ν1,O-H symmetric stretching  3450   cm−1
ν2, H-O-H bending 1640 cm−1                                     
ν3, O-H asymmetric stretching 3615 cm−1
ν1,O-H symmetric stretching 3400 cm−1        
ν2, H-O-H bending 1620 cm−1                                     
ν3, O-H asymmetric stretching 3220 cm−1

4. ATR-FTIR of Water Dynamics
The stretching band in liquid water is shifted to a lower frequency (v3, 3490 cm-1 and v1, cm-1 and the bending frequency increased (v2, cm-1 by hydrogen bonding. An increase in the strength of hydrogen bonding typically causes red-shift with greatly increased intensity
Rotations in the liquid phase are totally dominated by hydrogen bonding.
Libration is a type of reciprocating motion in which an object with a nearly fixed orientation repeatedly rotates slightly back and forth.
As water molecule is attracted to neighboring molecules, so it has a preferred orientation and cannot freely rotate.
Of course, when the neighboring molecules move around and the preferred orientation changes which are measureable in an infrared absorption spectrum

5. ATR-FTIR of Water Dynamics
The stretching band in liquid water is shifted to a lower frequency (v3, 3490 cm-1 and v1, cm-1 and the bending frequency increased (v2, cm-1 by hydrogen bonding. An increase in the strength of hydrogen bonding typically causes red-shift with greatly increased intensity
Rotations in the liquid phase are totally dominated by hydrogen bonding.
Libration is a type of reciprocating motion in which an object with a nearly fixed orientation repeatedly rotates slightly back and forth.
As water molecule is attracted to neighboring molecules, so it has a preferred orientation and cannot freely rotate.
Of course, when the neighboring molecules move around and the preferred orientation changes which are measureable in an infrared absorption spectrum

6. Effect of temperature and Pressure on ATR-FTIR bands of Water
Recent work, using attenuated total reflectance (ATR) infrared spectroscopy, shows that H2O observes isobestic points at 600, 1600, 1680 and 3550 cm-1
Increasing the pressure on water decreases the O····O distances
which increases the covalent O-H
distances and lowers their stretch frequency.
An increase in pressure also causes a reduction in long, weak or broken bonds
and an increase in bent and short, strong hydrogen bonds. Of course, when the neighboring molecules move around and the preferred orientation changes which are measureable in an infrared absorption spectrum

7. Variation in IR regions of water
Especially near IR vary
With temperature and
Chemical composition
This provides basis for
A non-destructive Composition analysis
Comparison of affected cites with healthy one
Structural and conformation variation in protein integrity of biological systems
Adulteration/contamination studies
Understanding the role of water in biological system
The near-infrared (NIR) bands (at about λ nm) are suited to rapid non-destructive water determination
* The whole scenario demands that Intensity of the OH Stretching Band of Liquid Water should Revisited

8. A groundbreaking story
A groundbreaking invention in this context has been reported on June 29, 2017 by Refael Minnes of Ariel University, Ariel, Israel (nature.com) Who applied ATR-FTIR to distinguish between melanoma cells with a different metastatic potential.
The methodology applied involved the investigation of intermolecular structure of water/dynamics and hydration level of cells following ATR-FTIR
Water in the biological system is present either as Low Density Water (H-bond with water molecules) or High Density Water (H-bond with other biological molecules)
It is understood that molecular LDW (3200 cm-1) and HDW (3400 cm-1) would differs in stretching vibrations
A significant spectral difference was observed between the cells of various metastatic states

9. Applications/Prospectus
Hyperspectral imaging is an emerging and rapid technique for nondestructive food analysis
This techniques involve the processing of either the visible-short near-infrared (vis-NIR; 400−1000 nm) or near infrared (NIR; 1000−1700 nm) spectral data
In another report Near Infrared Spectroscopy (NIRS) was used to Analyze Phenolic Compounds in Plants
Non-ionising IR thermal imaging has many advantages. Although not used routinely as a diagnostic clinical tool, it does have potential as a future imaging modality provided that image analysis can be developed to provide reliable routes to interpretation, assessment and diagnosis in medicine