Instrumentation of IR Spectroscopy and MCQ

 INSTRUMENTATION OF IR SPECTROSCOPY

There are mainly five part of IR spectroscopy which are as follows

1. Radiation source
2. Sampling
3. Monochromator
4.  Detector
5. Recorder

1. Radiation source :– There are mainly three types of radiation source are used.

A. Globar source :- It is consists of silicon carbide rod. When heating at 1300c- 1700c. It is produced IR radiation.

B. Nernst glower :- IT is consists of zirconium oxide, chromium oxide and yetrium oxide. It is produced IR radiation when heating at 1000-1800c.

C. Incandescent lamp :- it is consistent of nichrome coil in a glass tube. When it is heating at 1100c.

2. Sampling technique :-

There are mainly two types of sampling technique in IR

• 1. solid sampling technique
• 2. Liquid sampling technique

1.solid sampling technique

A. pelletization :- In this technique we are using diluent like NACL or KCL which are IR inactive compound. We mixed with NACL and sample and mix by motra and piston. After it is compressed it and prepare pellets. This pellets we put in sample holder.

B. Muling :- the sample can be mixed with Nujol ( mineral oil) and is applied on a liquid sample cell.

2. Liquid sampling :-

Sample can be held using a liquid sample cell made of alkali halide.

Aqueous solvent cann’t be used as they will dissolve alkali halide. Only organic solvent like chloroform is used.

3. Monochromator :- filter made up of lithium flouride or prisms made of potassium bromide, like alkali metal halide.

4. Detector :- To measure the intensity of unabsorbed IR,we used different type of detector like,

1. Thermocouple :– In this detector we are detected potential different between two junction.
2. Bolometers :–  Thin metal conductor. This detector work on sample principal that increase in temp. When IR radiation come. So, ultamitely increase resistance and current flow is change.
3.  Thermistor :- fused metal oxide mixture increasing temp. Decrease resistance by 5% at 1c.­

5. Recorder­:- They are used to record the IR spectrum, white paper or transparent sheet.

Reference for the analysis of book third edition Dr. S. ravi sankar.

MCQ

1. Nujol mean

A. Polymer

B. Crude oil

C. Mineral oil

D. Volatile oil

Ans.C

2. Which of the following is used in calibration of IR instrument ?

A. TMS

B. Glass

C. Mental halide

D. Poly styrene

Ans. D

3. Which material are used to prepare rod of globar source ?

A. Silicon dioxide

B. Silicon carbide

C. Silicon oxide

D. All of the above

Ans.B

4.Which temperature is required for nernst glower to produce IR radiation ?

A. 1000-1800 c

B. 1330- 1200 c

C. 800- 900 c

D. 100-300 c

Ans A

5. Which compound are used as diluent in IR sampling ?

A. alkali halide

B. keton

C. Aldehyde

D.  Acetone

Ans. A

6. Monochromator filter are made up of _?

A. Hydrogen peroxide

B. Silicon

C. Lithium flouride

D. All of the above

Ans . C

7. Which detector are detected IR radiation by potential different ?

A. Thermocouple

B. Bolometers

C. Thermistor

D. None of this

Ans. A

8. Nernst glower consists of

A. Ziroconium

B. Yetrium

C. Chromium

D. All of the above

Ans .D

9.  Incandescent lamp how much temperature is  Required to produce IR radiation ?

A. 1100 c

B. 800 c

C 300 c

D. 1400 c

Ans. A

10. Globar source required IR radiation temperature?

A. 1000 – 1800 c

B. 1000 – 1100 c

C. 700-800 c

D. 6000c

Ans. A

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