High-resolution inelastic X-ray scattering studies of the state-resolved differential cross-section of Compton excitations in helium atoms

TL;DR

This study uses high-resolution inelastic X-ray scattering to measure state-resolved differential cross sections for helium atom excitations, providing a precise test of theoretical models and demonstrating IXS's effectiveness in atomic and molecular studies.

Contribution

First measurement of helium atom excitation cross sections over a large momentum transfer region using high-resolution IXS, validating theoretical calculations.

Findings

Excellent agreement between measurements and theory

Demonstrates IXS as a powerful atomic excitation probe

Provides detailed data for specific helium transitions

Abstract

The state-resolved differential cross sections for both the 1s2 1S0 - 1s2s 1S0 monopolar transition and the 1s2 1S0 - 1s2p 1P1 dipolar transition of atomic helium have been measured over a large momentum transfer region by the high-resolution inelastic X-ray scattering (IXS) for the first time. The almost perfect match of the present measurement with the theoretical calculations gives a stringent test of the theoretical method and the calculated wavefunctions. Our results demonstrate that high-resolution IXS is a powerful tool for studying the excitations in atoms and molecules.