Atomic and Molecular Physics [GATE (Graduate Aptitude Test in Engineering) Physics]: Questions 18 - 21 of 58

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Question 18

Appeared in Year: 2011

Question

MCQ▾

For a multi – electron atom specify the one – electron orbital angular momentum, total orbital angular momentum and total spin angular momentum, respectively. The selection rules for electric dipole transition between the two electronic energy levels, specific by are –

Choices

Choice (4)Response

a.

b.

c.

d.

Question 19

Atomic and Molecular Physics
Population Inversion

Appeared in Year: 2011

Question

MCQ▾

The population inversion in a two level laser material cannot be achieved by optional pumping because,

Choices

Choice (4)Response

a.

The upward transition are allowed but downward transition are forbidden

b.

The rate of upward transition is equal to the rate of downward transitions

c.

The spontaneous decay rate of the higher level is very low

d.

The upward transition are forbidden but downward transition are allowed

Question 20

Atomic and Molecular Physics

Appeared in Year: 2011

Question

MCQ▾

The far infrared rotational absorption spectrum of a diatomic molecule shows equidistance lines with spacing . The position of the first Stokes line in the rotational Raman spectrum of this molecule is –

Choices

Choice (4)Response

a.

b.

c.

d.

Question 21

Appeared in Year: 2010

Question

MCQ▾

Two states of an atom have definite parities. An electric dipole transition between these states is

Choices

Choice (4)Response

a.

Allowed if both the states have even parity

b.

Allowed if both the states have odd parity

c.

Not allowed unless a static electric field is applied

d.

Allowed if the two states have opposite parities

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