Ionized Nitrogen Mono-hydride Bands are Identified in the Pre-solar and Carbonado Diamond Spectra

TL;DR

This study identifies ionized nitrogen mono-hydride (NH+) bands in pre-solar and carbonado diamond spectra, revealing that these diamonds contain only single nitrogen impurities and clarifying previous ambiguities in nitrogen-related spectral features.

Contribution

The paper introduces the identification of NH+ bands as nitrogen-related features in diamond spectra, providing a new understanding of nitrogen impurities in pre-solar and carbonado diamonds.

Findings

NH+ bands are present in both spectra.

All nitrogen-related bands are now assigned to NH+ defects.

Pre-solar and carbonado diamonds contain only single nitrogen impurities.

Abstract

None of the well established Nitrogen related IR absorption bands, common in synthetic and terrestrial diamonds, have been identified in the pre-solar diamond spectra. In the carbonado diamond spectra only the single nitrogen impurity (C centre) is identified and the assignments of the rest of the nitrogen-related bands are still debated. It is speculated that the unidentified bands in the Nitrogen absorption region are not induced by Nitrogen but rather by Nitrogen-hydrides because in the interstellar environment Nitrogen reacts with Hydrogen and forms NH+; NH; NH2; NH3. Among these Hydrides the electronic configuration of NH+ is the closest to Carbon. Thus this ionized Nitrogen-mono-hydride is the best candidate to substitute Carbon in the diamond structure. The bands of the substitutional NH+ defect are deduced by red shifting the irradiation induced N+ bands due to the mass of the additional Hydrogen. The six bands of the NH+ defects are identified in both the pre-solar and the carbonado diamond spectra. The new assignments identify all of the nitrogen-related bands in the spectra, indicating that pre-solar and carbonado diamonds contain only single nitrogen impurities.