Electronic Spectra of Corannulenic Cations and Neutrals in Neon Matrices and Protonated Corannulene in the Gas Phase at 15 K

Abstract

Three absorption systems starting at 624.1, 601.2, and 590.0 nm were detected in a 6 K neon matrix following deposition of mass selected

Spectroscopy of corannulene cations in helium nanodroplets

“…Since this absorption feature is so broad, we are not able to identify any shift in its position as a function of the number of solvating He/D 2 units. The position of this band is in agreement with the S 3 ( 1 A) ← S 0 ( 1 A) transition of protonated corannulene that was measured using a resonant multiphoton fragmentation technique in an ion trap as a broad peak near 5150 Å 23. The width of this peak, FWHM ≈ 800 Å, can be explained by a short-lived S 3 ( 1 A) state with a lifetime of ≈2 fs, though unresolved vibrational excitations could contribute to the width making this lifetime a lower limit estimate.…”

“…The position of this band is in agreement with the S 3 ( 1 A) ← S 0 ( 1 A) transition of protonated corannulene that was measured using a resonant multiphoton fragmentation technique in an ion trap as a broad peak near 5150 Å. 23 The width of this peak, FWHM ≈ 800 Å, can be explained by a short-lived S 3 ( 1 A) state with a lifetime of ≈ 2 fs, though unresolved vibrational excitations could contribute to the width making this lifetime a lower limit estimate. With no narrow bands originating from protonated corannulene in our measurements, it is unlikely that this system is responsible for any DIBs in this wavelength range.…”

“…We do not conclusively assign the other seven bands that we identify, but expect that vibrational excitations of the S 3 state contribute to them. Calculations show that transitions to the S 4 ( 2 A′)/S 4 ( 2 A′′) states may also be responsible for some of these bands 23…”

“…Calculations show that transitions to the S 4 ( 2 A )/S 4 ( 2 A ) states may also be responsible for some of these bands. 23 For each of the bands labeled in Figure 1 we have performed a least square fit of a Gaussian line profile. This was then repeated for the corresponding spectra with more He atoms attached to the C 20 H + 10 ions.…”

Infrared Spectrum of Protonated Corannulene H+C20H10 in Solid para-Hydrogen and its Potential Contribution to Interstellar Unidentified Infrared Bands

“…Figure shows possible sites for protonation of corannulene. Some quantum-chemical computations of the relative energies of isomers of protonated corannulene are reported. − Frash et al calculated these energies and concluded that the protonation at the hub -site has the least energy and those at the rim - and spoke -sites have energies higher by 8 and 57 kJ mol –1 , respectively …”