Laboratory IR Spectra of the Ionic Oxidized Fullerenes C₆₀O⁺and C₆₀OH⁺

[Image: see text] We present the first experimental vibrational spectra of gaseous oxidized derivatives of C(60) in protonated and radical cation forms, obtained through infrared multiple-photon dissociation spectroscopy using the FELIX free-electron laser. Neutral C(60)O has two nearly iso-energetic isomers: the epoxide isomer in which the O atom bridges a CC bond that connects two six-membered rings and the annulene isomer in which the O atom inserts into a CC bond connecting a five- and a six-membered ring. To determine the isomer formed for C(60)O(+) in our experiment—a question that cannot be confidently answered on the basis of the DFT-computed stabilities alone—we compare our experimental IR spectra to vibrational spectra predicted by DFT calculations. We conclude that the annulene-like isomer is formed in our experiment. For C(60)OH(+), a strong OH stretch vibration observed in the 3 μm range of the spectrum immediately reveals its structure as C(60) with a hydroxyl group attached, which is further confirmed by the spectrum in the 400–1600 cm(–1) range. We compare the experimental spectra of C(60)O(+) and C(60)OH(+) to the astronomical IR emission spectrum of a fullerene-rich planetary nebula and discuss their astrophysical relevance

Context-dependent detection of fungal parasites in four ant species

The reaction between the allyl radical (C3H5˙) and acetylene (C2H2) in a heated microtubular reactor has been studied at the VUV beamline of the Swiss Light Source. The reaction products are sampled from the reactor and identified by their photoion mass-selected threshold photoelectron spectra (ms-TPES) by means of imaging photoelectron photoion coincidence spectroscopy. Cyclopentadiene is identified as the sole reaction product by comparison of the measured photoelectron spectrum with that of cyclopentadiene. With the help of quantum-chemical computations of the C5H7 potential energy surface, the C2H2 + C3H5˙ association reaction is confirmed to be the rate determining step, after which H-elimination to form C5H6 is prompt in the absence of re-thermalization at low pressures. The formation of cyclopentadiene as the sole product from the allyl + acetylene reaction offers a direct path to the formation of cyclic hydrocarbons under combustion relevant conditions. Subsequent reactions of cyclopentadiene may lead to the formation of the smallest polycyclic aromatic molecule, naphthalene