Progress on inner-shell excitations of molecular van der Waals clusters

Area of Science:

• Atomic and Molecular Physics
• Physical Chemistry
• Surface Science

Background:

• Core-level spectroscopy probes electronic structure and chemical environments.
• Van der Waals clusters provide model systems for studying molecule-molecule interactions.
• High spectral resolution is crucial for detecting subtle spectral shifts.

Purpose of the Study:

• To investigate core-level excitation spectra of molecular van der Waals clusters.
• To characterize spectral shifts and line broadening in clustered carbon monoxide (CO).
• To understand intermolecular interactions and dynamic effects in molecular clusters.

Main Methods:

• Utilizing state-of-the-art storage-ring facilities.
• Employing insertion devices and high-resolution soft X-ray monochromators.
• Performing vibrationally resolved core-level spectroscopy on isolated and clustered CO.

Main Results:

• Observed characteristic line broadening for the C 1s --> pi* (v = 0) band in clustered CO.
• Detected a small red shift of 2 +/- 1 meV for the clustered CO spectrum compared to isolated CO.
• Experimental results align with theoretical frameworks like the quasi-atomic approach.

Conclusions:

• Intermolecular interactions significantly influence core-level excitation spectra in molecular clusters.
• Freezing of molecular rotations and dynamic localization are key factors affecting spectral features.
• High-resolution core-level spectroscopy is a powerful tool for probing cluster dynamics and interactions.