Metastable states in NO2+ probed with Auger spectroscopy.

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Spectroscopy

Background:

• Nitric oxide (NO) is a crucial molecule in various chemical and biological processes.
• Understanding the electronic structure of core-excited and ionized states is vital for predicting chemical reactivity.
• Previous studies have provided limited information on the dicationic states of NO.

Purpose of the Study:

• To present high-resolution N 1s and O 1s photoelectron spectra (PES) and Auger electron spectra (AES) of NO.
• To investigate the electronic structure, potential energy curves, and vibrational properties of core-ionized states and metastable dicationic states of NO.
• To assign previously unobserved Auger transitions to specific excited states of NO(2+).

Main Methods:

• High-resolution N 1s and O 1s photoelectron spectroscopy (PES).
• Auger electron spectroscopy (AES).
• Theoretical calculations of potential-energy curves for NO(2+).
• Franck-Condon analysis of vibrational progressions in AES.

Main Results:

• Detailed information on equilibrium distances, vibrational energies, and lifetime widths of core-ionized NO states was obtained from PES analysis, considering spin-orbit splitting.
• Five metastable dicationic final states of NO were observed in AES, including two previously unobserved states.
• Franck-Condon analysis provided insights into the potential-energy curves of dicationic states and relative Auger rates.
• Calculated potential-energy curves for NO(2+) showed good agreement with experimental results.

Conclusions:

• The study successfully assigned two previously unresolved Auger transitions to the C(2)Σ(+) and c(4)Π excited states of NO(2+).
• The combined experimental and theoretical approach provides a comprehensive understanding of the electronic structure and dynamics of core-excited and ionized NO.
• This work advances the characterization of NO dicationic states, contributing to fundamental knowledge in molecular physics and chemistry.