Question

3. Draw a Jablonski diagram and label absorption, internal conversion, vibration relaxation, intersystem crossing, fluorescence and phosphorescence processes. What are the characteristic time scales for absorption, fluorescence, phosphorescence, and vibrational relaxation transitions?

Answer 1

Jablonski diagram is an energy diagram which represents various transitions.This shows various elecronic states which includes several vibrational states in them.It explains the several possibilities or transition that may happen after absorption of light.

TABLONSKI DIAGRAM The Internal sasensin 1 a Teton septen vang vibedmal dortisory (1) Absorption Phaphosune (3) In Jablonski diagram two lines of process takes place 1. Radiative - In these transition radiation is being emitted and it densted in this diagram by a straight lone (-) 3. Non- Radiative - In these transitions radiation is not being emitted and they are denoted by curly arrow (MM). Time scales for Each process. 1. Absorption - Generally, the first transition is absorption in which am election is exuted from a lower energy level to a higher energy level. Its characteristic time scale is - 10-15 seconds. (2) Fluorescence. This tramation involve the return of the activated molecule from singlet exuted state (sa) to ground state (so). The radiation emitted in this process is called fluorescence. Its characteristic time scale is 10-9-10 7 seconds

3) Phosphores molecules from Phosphorescence. This tramstim involve the return of activated mo • from excited triplet stake (Ti) to ground state (so). The ation emitted in this transition is Phosphorescence " characturistic time scale is 10 - 10 seconds. The characterist Vibrational Relaxation - This is a non- radiative prouss in which he emergy deposited by the photon into the election is transferred to other vibrational leve Its characteristic time scale is loth_lo- seconds 5) Intermal conversion (1) - In internal conversion an exuted electron can transferred from a vibrational level in one electronic state to another vibrational state in lower electronic state. The characteristic time scale is about less than 10 seconds 6) Intersystem crossing (Isc) - In this process the transition takes plaus between states of different multiplicaties like from exited singlet State (s) to encited tribet state (1) Such transitions are Forbidden and hemu slow. The characteristic time scale is 10-8-10-3 seconds.