1

“INFRARED SPECTROSCOPY AND ITS RECENT APPLICATIONS”

JAIPUR

Submitted By : Supervised By : DEEPAK KUMAR KHANDELWAL Mr. ASHISH AGARWAL B. PHARM. Part - IVth M.PHARM.(Lecturer) Enroll. No. 06/15427 SKIP, JAIPUR SWAMI KESHVANAND INSTITUTE OF PHARMACY JAIPUR-302025

2

CONTENTS

Introduction to Spectroscopy

Infrared spectroscopy

Advanced infrared spectroscopy techniques

General applications

Recent applications

Limitations

References

3

Spectroscopy

Spectrum

A display of such data is called a spectrum, that is, a plot of the intensity of emitted or transmitted radiant energy (or some function of the intensity) versus the energy of that light.

Origin of spectra

The spectrum is originated from atoms ions and molecules by emitting or absorbing the energies.

Definition Spectroscopy is the study of the properties of material systems by means of their interaction with electromagnetic radiation; ordinarily the radiation is dispersed into a spectrum after passing through the material.

4

Common types of spectroscopy

Atomic spectroscopy

Molecular spectroscopy

Visible

Ultraviolet

Infrared

Raman

Nuclear magnetic resonance

Electron spin

Mass

5

Infrared spectroscopy

What is IR spectroscopy?

Infrared spectroscopy is the subset of spectroscopy that deals with the infrared region of the electromagnetic spectrum. It covers a range of techniques, the most common being a form of absorption spectroscopy.

Wavelength The wavelength range of infrared radiation lies between 14000–10 cm−1 (0.8–1000 μm) . The most useful I.R. region lies between 4000 - 670cm-1.

Regions

Near infrared :- approximately 14000–4000 cm−1 (0.8–2.5μm)

Mid infrared :- approximately 4000–400 cm−1 (2.5–30μm)

Far infrared :- approximately 400–10 cm−1 (30–1000 μm)

6

Modes of vibrations

1. Stretching : Change in inter-atomic distance along bond axis.

Symmetrical

Asymmetrical

7

2. Bending: Change in angle between two bonds. There are four types of bend.

Rocking

Wagging Twisting

Scissoring

8

Instrumentation

1. Sources

2. Monochromators

3. Sample preparation

4. Detectors

5. Typical method

9

1. Sources An inert solid is electrically heated to a temperature in the range 1500-2200 K. The heated material will then emit infrared radiation.

Nernst glower

Globar source

Incandescent wire source

Mercury arc

2. Monochromators

A monochromator is an optical device that transmits a mechanically selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input.

Prism monochromator

Grating monochromator

10

3. Sample preparation

Solid samples

Solid run in solution

Solid films

Mull techniques

Pressed pellet techniques

Liquid samples

Gaseous samples

11

Thermocouples

Photoconducting

Bolometers

Thermistors

Semiconductor detector

Pyroelectric detectors

4. Detectors

12

Fig:- Typical apparatus

5. Typical method

13

Advanced infrared spectroscopy techniques

1. Fourier transform spectroscopy

2. Two-dimensional infrared spectroscopy

3. Nonlinear two-dimensional infrared spectroscopy

14Fig:- Fourier transform spectrograph

1. Fourier transform spectroscopy It is a measurement technique whereby spectra are collected based on measurements of the coherence of a radiative source, using time-domain

measurements of the electromagnetic radiation.

15

2. Two-dimensional infrared spectroscopy

It is a technique for 2D correlation analysis of infrared spectra by extending the spectral information of a sample. The 2D spectra represent a graphical overview of the spectral changes due to changing concentration or changing temperature as well as the relationship between the spectral changes at two different wavenumbers.

It is a technique that has become available with the development of femtosecond infrared laser pulses. In this experiment first a set of pump pulses are applied to the sample. This is followed by a waiting time, where the system is allowed to relax. The waiting time typically lasts from zero to several picoseconds and the duration can be controlled with a resolution of tens of femtoseconds. A probe pulse is then applied resulting in the emission of a signal from the sample.

3. Nonlinear two-dimensional infrared spectroscopy

16

General Applications of IR spectroscopy

Identification of all types of organic compounds Identification of many types of inorganic compounds Determination of functional groups in organic materials Determination of the molecular composition of surfaces Detection of water in a sample Quantitative determination of compounds in mixtures Determination of molecular conformation Determination of molecular orientation (polymers and solutions) Identification of compounds by matching spectrum of unknown compound with

reference spectrum (fingerprinting) Identification of functional groups in unknown substance Identification of reaction components and kinetic studies of reactions Identification of molecular orientation in polymer films Detection of molecular impurities or additives present in amounts of 1% and in some

cases as low as 0.01% Identification of polymers, plastics, and resins Analysis of formulations such as insecticides and copolymers

17

Examples:-

18

19

Recent applications of IR spectroscopy

2. Atmosphere and the Environment 3. Combustion and Fire Detection

1. Imaging of human hair

4. Measuring Electric and Magnetic Fields

5. Spectroscopy and Technique Development

6. Process Monitoring and Industrial Hygiene

7. Forensic Applications

20

Cuticle

Cortex

Medulla

A

B

Fig:-Images based on the absorption of the CH stretching band (collagen) (A), the Amide I band (protein) (B), of hair.

1. Imaging of human hair

21

2. Atmosphere and the Environment

Airborne Humidity Measurements

By fast (25 Hz) and accurate (5%) hygrometer

Measurement of Greenhouse Gas Fluxes

NSF's HIAPER Gulfstream-V aircraft

A diode laser-based instrumentation for measurement of methane flux from natural and man-made sources.

22

3. Combustion and Fire Detection

Measurement of Flame Species

Real Time Imaging of Flame Species

Measurement of Combustion Radicals

4. Measuring Electric and Magnetic Fields

Frequency-resolved optical gating (FROG) uses a nonlinear optical material to slice out part of the ultrafast pulse, which is then measured with a spectrometer. A series of these slices produces an interferogram, which characterizes the time-dependent spectrum of the pulse.

23

5. Spectroscopy and Technique Development

Detection of Ammonia and Nitric Oxide Using Antimonide Diode Lasers

1. Nitric oxide (NO) in the 2650 nm region. 2. Ammonia (NH3) in the 2220 nm region

Diode Laser Absorption

Using this technique, we have demonstrated an absorption detection sensitivity equivalent to measuring a change of one part in one ten-millionth of the laser intensity. This high sensitivity provides a capability for measurement of very small trace gas concentrations (sub-ppm or even sub-ppb).

24

6. Process Monitoring and Industrial Hygiene

Semiconductor Process Gas Purity

Fig:-Near-IR diode laser

Perimeter Monitors for Hazardous Gases

A prototype diode laser-based instrumentation for perimeter monitoring of hazardous gases (e.g. hydrogen fluoride or hydrogen sulfide) in refineries or chemical plants (i.e. prototype HF monitor).

25

7. Forensic Applications

Analyzing Alcohol By a CMI INTOXILIZER

Analyzing Fibers Analyzing Drugs

Analyzing Paint

Heroine

cocaine

exp:-polyester, nylon, or acrylic

car, or on a weapon or someone's clothing or a room

26

Limitations

General

• Minimal elemental information is given for most samples.

• Background solvent or solid matrix must be relatively transparent in the spectral region of

interest.

• Molecule must be active in the IR region.

Accuracy

In analysis of mixtures under favorable conditions, accuracy is greater than 1%. In routine

analyses, it is ± 5%.

Sensitivity and Detection Limits

Routine is 2%; under most favorable conditions and special techniques, it is 0.01%.

27

References:-

1. Robert d. Braun ; “Introduction to instrumental Analysis”; Pharmamed Press Publishers; Indian Reprint edition-2006; P.no.-346-408.

2. Gurdeep R. Chatwal, Sham K. Anand; “Instrumental method of chemical Analysis”; Himalaya publishing house , Mumbai; Fifth edition-2002,Rprint-2008; p. no. 2.29-2.82.

3. http://en.wikipedia.Org/wiki/IR Spectroscopy;06/08/09.

4. http://en.wikipedia.Org/wiki/F.T. Spectroscopy;06/08/09.

5. http://www.cem.msu /edu/~reusch/virtual text/spectroscopy/IR.htm;12/08/09.

6. http://teaching.shu.ac.uk/hwb/chemistry/tutorials/malspec/IR spec1.htm;12/08/09.

7. http://www.prenhall.com/settle/chapters/ch.15.pdf;15/08/09.

8. http://www.answers.com/topic/IR-spectroscopy;15/08/09.

9. http://www. answers.com/spectroscopy;15/08/09.

28

10. http://en.wikipedia.Org/wiki/IR Spectroscopy/correlation table;24/08/09.

11. http://www.che.isu.edu/courses/4205/2000/hendren/application.html;24/08/09.

12. http://www.ijvs.com/volume2/edition4/section1.html;02/09/09.

13. http://www.chem.uga.edu/dluhy/pages/IR_spe_ip.htm;02/09/09.

14. http://orgchem.colorado.edu/hndbooks support/IR tutor/tutorial.html;11/09/09.

15. http://www. Swsciences.com/research opps.html;11/09/09.

16. http://en.wikipedia.org/wiki/Monochromators;14/09/09.

29

Thanks for your kind

attention

30

QUERIES????