Atomic, Molecular and Nuclear Physics — DU B.Sc. (Hons) Physics Previous Year Question Papers

: DSCAfoinic, Molecular andNuclear physics 2. Attempt five questions in all. 4. Attelapt/ozrr questions from the rest of the paper 1. Answer any six of the following: (6ZB-18) (a) What causes the fine structure of hydrogenic atoms? Q>) State and explain Lamor's theorem. (c) h the near infrared spectral of £2C£60 molecule there is an intense band at 2144c2'z'z-1. Calculate the zero point energy of the molecule. (d) Distinguish between Ranan scattering and Ra:yleich scattering. (e) What is the role of.neutrino in the phenomenon of p- decay? ® Write the law of conservation of momentum for the Gamow-Teller transitions. ts) Show how each line belonging to Lyman series splits into a doublet in Hydrogen atom. 2. (a) Derive an expression for the fine stmcture splitting of an (n, I) level of a hydrogeric system due to spin-orbit interaction. Calculate the magnitude of this shift in c77i-1 for 2Pi/z and 2p3/z states of the Hydrogen atom. a)hasten-Gerlachexperinent,abeamofsilveratomsmovesahorizontaldistance;f lm in a region with vertical magnetic field gradient 0.387 T/in. If the speed of silyer atomsisl00m/s,calculatethemaximumseparationbetweenthetracesonthedetector plates. [Given: Mass of silver atoms =1.79 x 10-25kg] (12+6) 3. (a) Give main featl]res of the pure .rotational band specthlm of a heteronuclear diatomic molecule. How are they explained, treating molecule as a rigid rotator. Also, discuss rotational spectrum of a diatomic molecule, treated as a non-rigid rotator. (b) In rigid rotator approximation for CO, the J = 0 → J = 1 absorption line occurs at a the CO molecule. frequency of 1.15 × 10'Iz. What is the (i) Moment of inertia and (i) bond length of (10+8) t. (a) Explain the classical theory of the observed Raman spectrum of a diatomic molecule Iow is it used to explain the structure of a diatomic molecule (b) Distinguish between Normal and Anomalous Zeeman Effects. Show that the total magnetic moment of an orbital electron in weak magnetic fields for the state with total angular momentum J is given by: (y = gHzJ/n (b) Give any three evidences indicating the presence of shell structure in nuclei. • (c) Predict the ground state spins, and parities based on the shell model for the following 6. (a) Give a brief account of multipole radiation associated with the process of y- decay. Consider a y transition from an initial excited state of angular momentum 3/2 and even parity to a final state 5/2 with even parity. What are the possible values of angular momentum for the multipole radiation emitted in the process? Determine the type of corresponding multipole radiation as eleciric or magnetic. (3) Descrile beidoes of electron capture. under wit contion is mr likely to cour (c) Draw and discuss the characteristic Morse potential energy curve for anharmonic vibrations of a diatomic molecule. (7+6+5) Useful information: ao 's the nope guant mabear charge, is the orbital quantum number and a is the