Electronic transitions in Rydberg Matter as the source of the unidentified infrared bands (UIR) observed in interstellar space

TL;DR

This paper refines the Rydberg Matter (RM) theory to better explain the unidentified infrared bands (UIR) observed in space, showing that stimulated emission from RM accounts for key spectral features and their variability.

Contribution

The paper introduces a simplified RM-based model that accurately describes UIR bands through stimulated emission, improving upon previous theoretical approaches.

Findings

UIR bands at 3.3 and 11.3 micrometers are due to deexcitation of Rydberg species.

High quantum number transitions (n=40-80 to 5-12) match observational data.

Variability of UIR bands is explained by changing excitation states of RM.

Abstract

Rydberg Matter (RM) theory is previously shown to give good agreement with the unidentified infrared bands (UIR, UIB) that are observed in emission from many objects in space. From stimulated emission studies in RM, a slightly simpler theoretical model is found that describes the transitions giving the UIR bands better. The general theory for RM was recently shown to be very accurate using rotational spectroscopy to observe several types of RM clusters (Mol. Phys. 105 (2007) 933). Two different large studies of UIR are now interpreted with the improved model. High-resolution UIR observations by Beintema et al. are interpreted as transitions from high levels n = 40 - 80 down to levels n = 5 - 12 in the final state. The upper level quantum numbers for the observed bands agree well with those found in experiments. The stationary UIR bands at 3.3 and 11.3 micrometer are due to deexcitation n = 9 -> 5 and 9 -> 7 of Rydberg species through stimulated emission. The other UIR bands vary considerably in wavelength in different environments and even with time as seen in numerous observational studies. Their great variability is difficult to model by the commonly used PAH model, but is a natural consequence of the varying excitation state of RM.