Electronic Spectroscopy of C ₆₀ ⁺ and Its Analogs C ₆₀ H ₂ O ⁺ , C ₆₀ H ⁺ , C ₆₀ D ⁺ , and C ₆₀ Mg ⁺

Abstract The fullerenes C 60 and C 70 have been detected in various interstellar environments, and the cation <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>60</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> has been identified as a carrier of at least four of the diffuse interstellar bands (DIBs). Based on the presence of fullerenes in space, it is plausible that certain fullerene analogs are abundant in interstellar environments as well. In this context, we present the first electronic laboratory spectra of the analogs C 60 H 2 O + , C 60 H + , C 60 D + , and C 60 Mg + . Furthermore, the electronic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>60</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> spectrum is remeasured and assignments of the observed transitions are proposed. In the spectrum of C 60 H 2 O + , several distinct absorption features could be detected between 10,300 and 10,800 cm −1 , whereas the analogs C 60 H + , C 60 D + , and C 60 Mg + show a broad absorption in the visible region between 17,000 and 25,000 cm −1 . None of the detected absorption features in these analogs of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>60</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> </mml:mrow> </mml:msup> </mml:math> could be assigned to DIBs.