VIDEO
HIGHLIGHT
Log InSign up
XPS Spectra for p, d, and f-orbitals
SummaryTranscriptChat

XPS Spectra for p, d, and f-orbitals

Understanding XPS Analysis: Peak Splitting and Intensity Ratios

Introduction to Orbital Splitting in XPS

  • The discussion begins with the explanation of why p, d, and f orbitals split into multiple peaks during X-ray Photoelectron Spectroscopy (XPS) analysis. It highlights the intensity ratios observed for these orbitals.
  • The speaker introduces the concept of total angular momentum (J), which is a combination of orbital angular momentum and spin angular momentum, crucial for understanding peak splitting.

Angular Momentum and Its Role

  • The relationship between orbital angular momentum (L) and its implications on peak intensities is discussed. For example, L = 0 results in a single peak for s orbitals.
  • An overview of electron behavior around the nucleus is provided, emphasizing both orbital motion and spin as contributors to total angular momentum.

JJ Coupling Explained

  • The concept of JJ coupling in quantum mechanics is introduced, explaining how it relates to spin-orbit splitting or doublets in spectral lines.
  • For p orbitals with L = 1, the presence of non-zero angular momentum leads to observable doublets in their spectra.

Deriving Intensity Ratios

  • A visual representation shows that smaller peaks indicate lower concentration elements; this observation supports the derived intensity ratios.
  • The nomenclature used to represent XPS peaks (n l j notation) is explained further, clarifying how principal quantum numbers relate to observed spectral features.

Proving P Orbital Intensity Ratios

  • To demonstrate why p orbitals have an intensity ratio of 1:2, a formula involving degeneracy (2J + 1) is referenced.
  • Using oxygen as an example, the speaker illustrates how splitting occurs within p orbitals leading to specific intensity ratios based on electron configurations.

D Orbitals Intensity Ratio Calculation

  • Similar calculations are applied to d orbitals where J values lead to a derived ratio of 6:4 or simplified down to 3:2 due to ten electrons present in d orbitals.
Playlists: XPS - X-rays Photoelectron Spectroscopy
Video description

Why the p, d and f orbitals have intensity ratio 1:2, 2:3, and 3:4, respectively? In XPS, the relative intensities are determined by 2j+1 nlj is the common nomenclature to represent any peaks in XPS analysis  n : principle quantum number  l : orbit angular momentum quantum number  j : total angular momentum quantum number; j = l ± s (where s =±1/2 is spin angular momentum) Subshell j values Area ratio s 1/2 NA p p1/2 & p3/2 1:2 d d3/2 & d5/2 2:3 f f5/2 &f 7/2 3:4 Let's prove it for p-orbital, where l=1 The intensity ratio of p1/2 & p3/2 is 1:2 corresponding to 2 electrons in the 2p3/2 level and 4 electrons in the 2p1/2 level. Similarly for d-orbital, where l=2 The intensity ratio for d5/2 & d3/2 is 3:2 Also for f-orbital, where l=3 The intensity ratio for f7/2 & f5/2 is 4:3 To sum up, the p, d, and f- orbitals doublets peaks appear in the ration of 1:2, 2:3, and 3:4, respectively. The 1:2 for p-orbital means that the 2p1/2 contains 2- electrons while the 2p3/2 orbital contains 4- electrons. Similarly, for d, and f-orbitals, the ration can be calculated by simply using 2j+1 formula. Please subscribe to my channel and share it. Thank you!