Potential vibrational modes tied to diffuse interstellar bands

ABSTRACT Potential vibrational modes associated with diffuse interstellar bands (DIBs) could be discerned by examining energy differences between correlated DIBs. Consequently, $\approx 10^3$ higher correlated DIB pairs ($r-\sigma _\mathrm{ r} \ge 0.8$, $\ge 12$ sightlines) were extracted from the Apache Point Observatory DIB catalogue, and their energy spacings computed. In this first macro exploratory step, a histogram possibly reveals chemical bond signatures of C$\equiv$C, C$\equiv$N, S–H, C–O, C$=$O, Si–H, N–H, C–H (aliphatic), C$\mathbf {^{\underline{...}}}$C (in-ring), and aromatics (C–H stretch, C$\mathbf {^{\underline{...}}}$C in-ring, oop C–H bending, overtones and combinations). Continued research is required to (in)validate the histogram approach, mitigate noise, scrutinize maxima, break degeneracies, and converge upon an optimal framework.