LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M. Sc. DEGREE EXAMINATION – PHYSICS

FIRST SEMESTER – NOVEMBER 2003

PH 1804 / PH 725 – SPECTROSCOPY

11.11.2003                                                                                              Max.   : 100 Marks

1.00 – 4.00

PART – A

 

Answer ALL the questions.                                                                         (10 x 2 = 20)

 

1. How are molecules classified on the basis of moment of inertia? Give one example for each.
2. The moment of inertia of OCS molecule is 137.95 x 10^-47 kg-m². Calculate the rotation constant.
3. What type of spectroscopy is best suited for H₂? Give reasons.
4. Explain with an example, the rule of mutual exclusion.
5. What is Fortrat parabola?
6. The band origin of a transition in C₂ is observed at 19378 cm^-1 while the rotational fine structure indicates that the rotational constants in excited and ground states are respectively B¹ = 1.7527 cm^-1 and B¹¹ = 1.6326 cm^-1. Estimate the position of the band head.
7. Define quadruple moment of a nucleus.
8. Give the importance of double resonance technique.
9. Calculate the magnetic field strength required to get transition frequency of 60 MHz for hydrogen nuclei.
10. A Mossbauer nucleus has spin 1/2 and 3/2 in the ground state and excited state respectively. Sketch the Spectrum when combined electric and magnetic fields are present.

PART – B

 

Answer any FOUR                                                                                     (4 x 7.5 = 30)

 

11. a) Explain the factors that determine the intensity of a spectral line. Obtain an expression for J at which maximum population occurs.

 

20. b) The separation between lines in the rotational spectrum of HCl molecules was found to be 20.92 cm^-1. Calculate the bond length.

 

12. a) How many normal modes of vibration area possible for H₂O? Show by sketch the fundamental vibrational modes of H₂O molecule.

 

1. b) Outline the theory of Raman spectrum on the basis of (1) Classical theory and (2) Quantum theory.

 

13. Explain the importance of Franck-Condon principle in explaining the intensity of molecular Spectrum.
14. Discuss the T₁ and T₂ relaxation mechanism in NMR. Derive an expression for the relaxation time T₁.
15. Explain with a neat diagram, the functioning of Electron energy loss spectrometer.

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PART – C

 

 

Answer any FOUR                                                                                   (4 x 12.5 = 50)

 

16. (a) Explain, with theory, the spectrum of a linear diatomic molecule of rigid rotor type. Deduce the correction for non-rigid type.

 

(b) Calculate the frequency of  NO  molecule whose force constant is 1609 Nm^-1.

 

17. (a) Explain Born-Oppenheimer      Describe, with theory,  the rotation – vibration spectra of a diatomic molecule.

 

(b) The fundamental and first overtone transition of   ¹⁴N, ¹⁶O are centered at 1876.06 cm^-1 and 3724.20 cm^-1 respectively. Equivalent the equilibrium frequency, anharmonicity constant and zero point energy.

 

18. Obtain an expression for the Dissociation energy of a molecule. The Vibrational Structure of the absorption Spectrum of O₂ becomes a continuum at 56,876 cm^-1. If the upper electronic state dissociates into one ground state atom and one excited atom with excitation energy 15,875 cm^-1, estimate the dissociation energy of ground state of O₂ in cm^-1 and kJ / mole.

 

19. Explain the principle of ESR. Sketch a neat diagram and explain the functioning of ESR Spectrometer.

 

20. Outline the importance of ‘RAIRS’ technique in characterising the absorbed surfaces on a specimen.

 

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 34.

1. Sc., Degree examination – PHYSICS

First semester – NOVEMBER 2004

PH 1804 –  Spectroscopy

 

Date : 25.10.2004                                       Max. 100 Marks

Duration: 9.00 – 12.00                         Hours : 3 Hrs

 

 

PART – A

 

 

Answer all the questions                                              (10 X 2 = 20)

 

1. Classify the type of molecule according to structure from the following list H₂O, CO₂, CCl₄, NH₃
2. Calculate the rotational constant of the H₂ molecule. Given that the H-H bond length is 74. 12 pm.
3. Sketch the fundamental vibrational modes of H₂O molecule
4. State the rule of mutual exclusion
5. What is Fortrat parabola? Explain its significance
6. The absorption spectrum of O₂ shows vibrational structure, which becomes continuum at 56.876 cm^-1. The upper electronic state dissociates into one ground state atom and one excited atom (spectral position at 15875 cm^-1). Estimate the dissociation energy of ground state O₂ in KJ/mol.
7. Calculate the value of nuclear magneton
8. Sketch the H-NMR spectrum of CH₃CH₂OH
9. Calculate the recoil velocity of a free Mossbauer nucleus of mass 1.67 X 10 ^–25 kg, when it emits gamma ray of wavelength 0.1 nm.
10. Mention any two limitations of surface spectroscopy

 

 

PART – B

 

Answer any four                                                  (4 X 7.5 = 30)

 

11. Obtain an expression for J for maximum population. The rotation spectrum of a sample has a series of equidistant lines spaced 0.7143 cm^-1 apart. Find which transition gives rise to the most intense spectral line at 27°C

 

12. Describe with theory the rotation – vibration spectra of a diatomic molecule

 

13. What is Franck-Condon principle? Using the same, explain the intensity of spectral lines

 

14. Discuss the effect of electric and magnetic fields on Mossbauer spectrum exhibited by ⁵⁷ Fe.

 

15. Outline the principle of Electron Energy Loss Spectroscopy and mention the applications

 

PART –  C

 

 

Answer any four                                                            (4 X 12.5 = 50)

 

16a) Explain, with necessary theory, the rotational spectrum of a diatomic molecule of the rigid-rotor type. Deduce the spectrum of non-rigid rotor type molecule.                                                                                        (10)

1. b) The bond-length of nitrogen molecule is 0.10976 nm. Calculate the seperation between Raman lines. (2.5)

 

17. a) Outline the theory of Raman effect on the basis of i) classical theory ii) quantum theory.                                                                    (8)
18. b) The fundamental band of CO is centered at 2143 cm^-1 and the first overtone band at 4259.7 cm^-1. Calculate i) fundamental frequency of vibration ii) anharmonicity constant iii) zero point energy (4.5)

 

18. Discuss in detail, the method of characterizing samples using Electron spectroscopy for chemical analysis

 

19. Discuss in detail, the shielding and de-shielding phenomenon in nuclear magnetic resonance spectroscopy. Explain how the spectral splitting is explained using family tree method.

 

20. Explain the principles of Auger electron spectroscopy.

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

FOURTH SEMESTER – APRIL 2012

PH 4807 – SPECTROSCOPY

 

 

Date : 18-04-2012             Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART – A

Answer ALL questions                                                                                                                   (10×2=20)

 

1. Explain with the help of an example for symmetric top and spherical top molecule
2. The rotational constant of NO is 41.7201 cm^-1. Calculate the moment of inertia of the molecule.
3. Explain Born-Oppenheimer approximation.
4. Bond length of N₂ molecule is 1.0907 . Determine the position of the first rotational Raman lines in the spectrum. Given mass of ¹⁴N = 23.25 x 10 ^-27
5. What is double resonance?
6. Distinguish between sequence and progression
7. An NMR signal for a compound is found to be 420 Hz downward from TMS operating at 600 MHz. Calculate shift in ppm.
8. Write a note on C¹³ spectroscopy with reference to chemical shift.
9. Distinguish between photoluminescence and fluorescence spectroscopy
10. Difference between inelastic scattering and elastic scattering

 

PART – B

Answer any FOUR questions                                                                                                                (4×7.5 = 30)

 

11. Explain with example, the effect of isotopic substitution on the pure rotational spectra of a diatomic molecule. The first rotational line of ¹²C¹⁶O is observed at 3.8425 cm^-1 and that of ¹³C¹⁶O at 3.67337 cm^-1. Calculate the atomic weight of ¹² C, assuming the mass of ¹⁶O to be 15.9949 a.m.u.
12. Outline the theory of Raman spectrum on the basis of i) classical theory and ii) quantum theory
13. With a neat diagram, explain the functioning of ESCA briefly.
14. What is indirect spin-spin interaction? Explain why many spectral lines are seen in the CH₃ and CHO protons of acetaldehyde?
15. Explain the functioning of XPES

 

PART – C

Answer any FOUR questions                                                                                                                 (4×12.5 =50)

 

16. Explain with theory, the spectrum of a linear diatomic molecule of rigid rotor type. Deduce the correction for non-rigid type.
17. a) Explain the theory of diatomic vibrating rotator on the basis of Bohr’s approximation.
18. b) The fundamental band of CO is centered at 2143 cm^-1 and the first overtone band at 4259 cm^-1. Calculate fundamental frequency of vibration, anhormonicity constant and zero point energy.
19. Give the selection rules associated with rotational fine structure of electronic vibration spectra. Explain the origin of P,Q and R bands and derive the energy expressions associated with the bands
20. Illustrate the decay scheme in ⁵⁷Co and ⁵⁷ With a block diagram explain the working of Mossbauer spectrometer
21. Explain the following electron spectroscopic techniques.
22. a) Auger electron (AES) and b) Fluorescence (XRF)

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

FOURTH SEMESTER – NOVEMBER 2012

PH 4807 – SPECTROSCOPY

 

 

Date : 07/11/2012            Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART – A

Answer ALL questions                                                                                              (10×2=20)

1. How are molecules classified on the basis of moment of inertia? Give one example each.
2. The rotational constant for HCl ³⁵ is observed to be 10.5909 cm^-1. Calculate the value of B for HCl ³⁷.
3. Show by sketch the fundamental vibrational modes of CO₂
4. Why are stokes lines more intense than antistokes lines?
5. What is continuum in the electronic spectra of a diatomic molecule?
6. Explain the term progressions
7. State the advantages of TMS when recording NMR spectra?
8. What is spin-lattice relaxation?
9. Give the principle of UPES?
10. Mention any two advantages of surface spectroscopy

 

PART – B

Answer any FOUR questions                                                                                                (4×7.5 = 30)

• Explain the factors that determine the intensity of a spectral line. Obtain an expression for J at which maximum population occurs. (5)

1. The rotational spectrum of BrF shows a series of equidistant spectral lines spaced 0.71433 cm^-1 apart. Find which transition will give rise to the most intense line at 300 K. (2.5)
2. Outline briefly each section of IR spectrometer. (5.5)
3. Calculate the frequency of NO molecule whose force constant is 1609 Ncm^-1. (7)
4. State and explain Franck-Condon principle. Explain how the intensity of spectral line is explained on the basis of it.
5. Obtain the expression for T₁ relaxation time in terms of transition probability
6. Explain how RAIRS spectroscopy is used for characterizing surfaces

 

PART – C

Answer any FOUR questions                                                                                                (4×12.5 =50)

16. a) Explain with theory, the spectrum of symmetric top molecule.
17. b) The three consecutive lines in the rotational spectrum of HBr are 84.544, 101.355 and 118.112 cm^-1. Find the values of rotational constant, centrifugal distortion constant and vibrational frequency.
18. Explain the theory of pure rotational Raman spectra of linear molecule and symmetric top molecule.
19. Explain band origin and band head in the rotational fine structure of electronic vibration spectra. Will there be a band at the band origin?
20. Discuss briefly the theory of NMR and explain the working of the spectrometer
21. Explain the principle and application of electron energy loss spectroscopy.

 

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