Observation of (N2)2 dimers in free nitrogen and argon-nitrogen clusters

TL;DR

This study used supersonic-jet luminescence spectroscopy to detect (N2)2 dimers inside nitrogen and argon-nitrogen clusters, revealing their potential role as fundamental units in nitrogen cluster formation and polymeric nitrogen synthesis.

Contribution

First observation of (N2)2 dimers inside small nitrogen clusters, indicating their importance in cluster structure and polymeric nitrogen formation.

Findings

Detection of (N2)2 dimers in nitrogen clusters

(N2)2 dimers observed in solid nitrogen phase

Implication of (N2)2 as building blocks for nitrogen polymers

Abstract

Supersonic-jet luminescence spectroscopy was applied to study vibronic transitions in icosahedral N2 and Ar-N2 clusters having from 100 to 400 particles per cluster. In the case of mixed Ar-N2 clusters, the w->X transitions were observed to occur in single N2 molecules in an Ar environment, that is very much in the same way as in Ar-N2 bulk samples. In N2 clusters, however, a band series was detected which was never observed earlier. In the spectra of Ar-N2 clusters, this new series coexisted with the 'bulk' w->X transitions. Our analysis demonstrated that the series should be assigned to emission of van der Waals (N2)2 dimers from inside clusters. Earlier, such dimers were only observed in molecular beams and gaseous nitrogen, this paper reports their observation in the solid phase of nitrogen suggesting that they may be the basic building blocks of small N2 clusters. Our results can be of interest from the viewpoint of producing polymeric nitrogen since (N2)2 dimers can be considered to be a starting species for its synthesis.