IR Absorptions of C₆₀⁺ and C₆₀^– in Neon Matrixes

Abstract

C60(+) ions were produced by electron-impact ionization of sublimed C60, collimated into an ion beam, turned 90° by an electrostatic deflector to separate them from neutrals, mass filtered by a radio frequency quadrupole, and co-deposited with Ne on a cold 5 K gold-coated sapphire substrate. Infrared absorption spectroscopy revealed the additional presence of C60 and C60(-) in the as-prepared cryogenic matrixes. To change the C60(+)/C60(-) ratio, CCl4 or CO2 electron scavengers were added to the matrix gas. Also taking into account DFT calculations, we have identified nine new previously unpublished IR absorptions of C60(+) and seven of C60(-) in Ne matrixes. Our measurements are in very good agreement with DFT calculations, predicting D5d C60(+) and D3d C60(-) ground states. The new results may be of interest regarding the presence of C60 and C70 (as well as ions thereof) in Space.

Near-IR Photoluminescence of C60+

“…The UHV experimental setup for optical spectroscopy of mass-selected species has already been described in our previous publications [9,19,20]. Briefly, C longpass filter (Thorlabs FELH0950) was used to detect the emission.…”

On observing C60+and C602+in laboratory and space

“…The IR and UV-NIR absorption spectra of C +/− 60 (Kern et al 2013) and C 2+/3+ 60 (Kern et al 2014) have been reported previously along with experimental procedures and data analysis methods. Briefly, samples were prepared through low-energy ion beam deposition into a cocondensed inert gas matrix doped with electron scavengers (CO 2 , CCl 4 ) as necessary to vary the resulting fullerene charge state distributions.…”

“…Absorptions of different C 60 charge states are indicated with 0, + and -for neutral, cation, and anion, respectively. been described in detail in our previous work (Kern et al 2013(Kern et al , 2014. IR frequencies of C 60 , C + 60 , and C − 60 absorptions in Ne and Ar matrixes are presented in Table 1 together with Ne data for C so far, we estimate the low-temperature gas-phase absorption frequencies from the matrix data.…”

“…On the basis of integrated molar absorptivities previously measured for C +/− 60 in the IR region (Kern et al 2013), the C + 60 NIR oscillator strengths are determined as f = 0.015 ± 0.005 for the 966 nm and f = 0.01 ± 0.003 for the 958 nm absorptions (see Fig. 2).…”

“…Many unknown absorptions were uncovered (Kern et al 2013). Furthermore, we have obtained first IR/NIR/UV spectra of C 2+/3+ 60 (Kern et al 2014).…”