Why does the photoelectron spectrum of solid sodium azide show two peaks in a 2:1 ratio?
MP Assistant Professor Exam 2022
Photoelectron spectrum of solid sodium azide excited by Al-K radiation exhibits two peaks in the ratio of 2:1. What is the reason of these two peaks?
- (A) 3 Nitrogen atoms
- (B) Two double bonds
- (C) Inequivalence of N atoms
- (D) Sodium azide is solid
Answer: (C) Inequivalence of N atoms
Explanation: The azide ion (N3−) is linear but its atoms are not all identical. It consists of two terminal nitrogen atoms (equivalent to each other) and one central nitrogen atom (electron-deficient/positively charged).
Because these two environments have different electron densities, the core electrons have different binding energies, resulting in two distinct peaks in a 2:1 intensity ratio.