Infrared spectroscopy of carbo-ions. VI. C–H stretching vibration of the acetylene ion C2H2+ and isotopic species

Citations Over TimeTop 10% of 1992 papers

Abstract

The infrared spectra of the band of the 2Π–2Π asymmetric hydrogen stretching vibration in the three isotopic acetylene ions C2H2+ (ν3), 13C2H2+ (ν3), and DCCH+ (ν1) have been observed and analyzed. The high resolution infrared spectra were recorded using a difference-frequency laser spectrometer as the tunable coherent infrared source probing an ac glow discharge. Velocity modulation, noise subtraction, and unidirectional multipassing of the infrared beam through the discharge cell provided high sensitivity. C2H2+ was produced in a gas mixture of H2, He, and either CH4 or C2H2, with a total pressure of ≊7 Torr in multiple-inlet–outlet air-, water-, and liquid-nitrogen-cooled discharge tubes; C2H2 freezing precluded its use in liquid-N2-cooled discharges. Complicated by a strong perturbation whose maximum occurred at N′=15 for F1 and N′=14 for F2, the assignment of the spectrum of normal C2H2+ was made possible by (1) fortuitous discharge conditions which provided unambiguous discrimination of C2H2+ lines from among concurrent CH3+ and C2H3+ lines, and (2) fitting the ground state combination differences. Sufficiently high N transitions were observed where Λ doubling was evident. The average bond lengths rz(CH)=1.077 (5) Å and rz(CC)=1.257 (8) Å were calculated from the spectroscopic constants determined from nonlinear least-squares fitting. Vibration–rotation interactions, the Renner–Teller interaction of perturbing states, plasma chemistry, and the relevance of the work in astrophysics are discussed.

Related Papers

• → Convoy electrons emitted from resonant coherently excited ions(1991)18 cited
• → Deexcitation and recombination of excited ions through doubly excited levels in a dense recombining plasma: Lithiumlike recombining plasma laser(1997)12 cited
• → Internal-energy-selected measurements of acetylene ions with acetylene at thermal energies(1988)9 cited
• → Dielectronic recombination in plasmas. II. Initial excited states(2001)1 cited
• → Autoionization of Doubly and Triply Excited States of Li+ and Li Produced in Li3+ Ion Collision with C60, Ar and Xe(2001)