Atomic & Molecular Physics-Population Inversion (CSIR Physical Sciences): Questions 1 - 2 of 2

Get 1 year subscription: Access detailed explanations (illustrated with images and videos) to 401 questions. Access all new questions we will add tracking exam-pattern and syllabus changes. View Sample Explanation or View Features.

Rs. 300.00 or

Question number: 1

» Atomic & Molecular Physics » Population Inversion

Appeared in Year: 2012

MCQ▾

Question

Consider the energy level diagram shown below, which corresponds to the molecular nitrogen laser.

 The energy level diagram

the Energy Level Diagram

In figure the energy level diagram is shown.

If the pimp rate R is 1020atomscm3s1 and the decay routes are as shown with τ21=20ns and τ1=1μs , the equilibrium populations of states 2 and 1 are respectively. (December)

Choices

Choice (4) Response

a.

1014cm3and2×1012cm3

b.

2×1012cm3and1014cm3

c.

zeroand1020cm3

d.

2×1012cm3and2×106cm3

Passage

1.6×1019 Chromium ions cubic centimeter. All the atoms excited by the 0.4μm radiation decay rapidly to level E2 which has a lifetime τ=3ms

Three energy levels for Chromium ions

Three Energy Levels for Chromium Ions

In figure three distinct energy levels are shown. All atoms excited by radiation decay.

(June)

Question number: 2 (1 of 1 Based on Passage) Show Passage

» Atomic & Molecular Physics » Population Inversion

Appeared in Year: 2011

MCQ▾

Question

Assuming that there is no radiation of wavelength 0.7μm present in the pumping cycle and that the pumping rate is R atoms per cm3 , the population density in the level N2 builds up as:

Choices

Choice (4) Response

a.

N2(t)=Rt2τ(1etτ)

b.

N2(t)=Rτ(etτ1)

c.

N2(t)=Rt

d.

N2(t)=Rτ(1etτ)

Sign In