UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper II

Q9. Franck–Condon principle: which v′ an electronic transition reaches

10 marks
Topic: Photochemistry
Question only

Question

Describe the changes observed in the vibrational quantum number in an electronic transition using Franck-Condon principle.

Model answer

The free solution for 2021 answers questions 1, 2, 3, 4, 6, 7, 10, 12, 14 and 15, the ones picked in its time plan. Question 9 is answered in full in the Geo-Scientist Chemistry Paper II, 2021 to 2025 book, with every part of every paper.

Read the 2021 solution

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

Printed copy and Kindle

UPSC Combined Geo-Scientist (Main) Chemistry Paper II: Model Answers 2021 to 2025

All fifteen questions of each paper, with the question printed above its answer
Numericals worked from formula to result with units; graphs with labelled axes
Topic-wise weightage and a topic-wise index

Printed copy Kindle edition Read sample pages

Topic notes: vibrational and electronic spectra (force constant, isotope effect, overtones, Franck–Condon), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversFranck–Condon principlevertical transitionelectronic spectravibrational quantum numberprogression