Line shapes of $1s\to {\pi }^{*}$ excited molecular clusters

The line shapes of $1s\to {\pi }^{*}$-excited molecular Van der Waals clusters are compared to those of the corresponding isolated molecules. Small, but distinct spectral changes are observed, such as spectral shifts, line broadening, and changes in intensity. These are assigned in terms of variations in motion of the core-excited molecule within the molecular clusters using a simple model. Contributions from intra- and inter-molecular vibrations in core-excited clusters, which contribute to the experimentally observed spectral changes, are discussed.

Figure 1

Cluster potentials and $\mathrm{N}1s$ $\left(v^{\prime }=0\right)\to {\pi }^{*}\left(v^{\prime }\right)$ transition in a linear chain of nitrogen molecules within (a) statistic $\left(U^{*}\right)$ and (b) dynamic $\left(U^{{*}_{\left(j\right)}}\right)$ models of the intermediate core-ionized cluster state (for details see text).

Figure 2

Near edge spectra of $\mathrm{C}1s$ and $\mathrm{O}1s$ excited $\mathrm{CO}$ and its clusters near the $1s\to {\pi }^{*}$-transition: (a) $\mathrm{C}1s$-regime; (b) $\mathrm{O}1s$-regime. See text for further details (cluster: recorded at $⟨N⟩\approx 150$).