GATE PH Atomic and Molecular Physics PYQs & Answers — Page 3

Questions 21–30 of 44. Imported answers require independent review unless marked reviewed.

Frequency bandwidth

of a gas laser of frequency

Hz is

where

at room temperature and

is the atomic mass of the lasing atom. For

laser (wavelength = 633 nm),

Hz. The value of

is ________ (Round off to one decimal place)

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Among the term symbols

and

choose the option(s) possible in the

coupling notation.

Your answerSelect all correct options. You can choose more than one.

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To sustain lasing action in a three-level laser as shown in the figure, necessary condition(s) is(are)

Your answerSelect all correct options. You can choose more than one.

lifetime of the energy level 1 should be greater than that of energy level 2

population of the particles in level 1 should be greater than that of level 0

lifetime of the energy level 2 should be greater than that of energy level 0

population of the particles in level 2 should be greater than that of level 1

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The spacing between two consecutive S-branch lines of the rotational Raman spectra of hydrogen gas is 243.2 cm

. After excitation with a laser of wavelength 514.5 nm, the Stoke’s line appeared at 1761.1 cm

for a particular energy level. The wavenumber (rounded off to the nearest integer), in cm

, at which Stoke’s line will appear for the next higher energy level is ______.

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The transition line, as shown in the figure, arises between

and

states without any external magnetic field. The number of lines that will appear in the presence of a weak magnetic field (in integer) is ______.

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Consider the atomic system as shown in the figure, where the Einstein A coefficients for spontaneous emission for the levels are

and

. If

atoms/cm

are excited from level 0 to level 2 and a steady state population in level 2 is achieved, then the steady state population at level 1 will be

. The value of

(in integer) is ______.

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The spin

and orbital angular momentum

of an atom precess about

, the total angular momentum.

precesses about an axis fixed by a magnetic field

, where

is a constant. Now the magnetic field is changed to

. Given the orbital angular momentum quantum number

and spin quantum number

is the angle between

and

for the largest possible values of total angular momentum quantum number

and its z-component

. The value of

(in degree, rounded off to the nearest integer) is _____.

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The spin-orbit effect splits the

transition (wavelength,

Å) in Lithium into two lines with separation of

Å. The corresponding positive value of energy difference between the above two lines, in eV, is

. The value of

(rounded off to the nearest integer) is _____.

(Given: Planck’s constant,

eV s

Speed of light,

m s⁻¹)

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Consider a diatomic molecule formed by identical atoms. If

and

represent the energy of the vibrational nuclear motion and electronic motion respectively, then in terms of the electronic mass

and nuclear mass

is proportional to

Your answerChoose one option.

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A hydrogen atom is subjected to a strong magnetic field. In the absence of spin-orbit coupling, the number of doubly degenerate states created out of the

-level is _____.

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GATE PH Atomic and Molecular Physics PYQs

Question 64

Question 14

Question 15

Question 22

Question 23

Question 24

Question 54

Question 55

Question 12

Question 20