Considering the following parameters with reference to the fluorescence of a solution:
1. Molar absorptivity of fluorescent molecule
2. Intensity of light source used for excitation
3. Dissolved oxygen
The correct answer for the enhancement of fluorescence with the increase in these parameters is/are
(a)1 and 2
(b)2 and 3
(c)1 and 3
(d)3 only
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
For a dilute solution the fluorescence intensity is F = 2.303 Φ_F P₀ ε b c, i.e. F ∝ Φ_F·P₀·ε·b·c. Increasing the molar absorptivity ε of the fluorescent molecule (statement 1) increases the light absorbed and hence F. Increasing the intensity P₀ of the excitation source (statement 2) also increases F proportionally. Dissolved O₂ (statement 3) is paramagnetic and quenches fluorescence (collisional quenching / enhanced intersystem crossing), so increasing it lowers F. Hence parameters 1 and 2 enhance fluorescence — option (a).