"Heavy Electron" Photoelectron Spectroscopy: Rotationally Resolved Ion Pair Imaging of CH ₃ ⁺

Abstract

We applied the velocity map imaging technique under high-resolution conditions to study ion pair products of the vacuum ultraviolet photodissociation of methyl chloride. We obtained rotationally resolved kinetic energy release spectra that directly provide vibrational frequencies and rotational constants of the fundamental carbocation, CH3+. The technique is analogous to photoelectron spectroscopy, with the chloride anion playing the role of a "heavy electron." The approach shows promise as a general probe of ionic species not amenable to study by traditional methods.

Anharmonic vibrational frequencies and vibrationally-averaged structures of key species in hydrocarbon combustion: HCO+, HCO, HNO, HOO, HOO–, CH3 +, and CH3

“…Oka and co-workers [195][196][197] observed the accurate frequency of the degenerate C-H stretch ( 3 ) by infrared spectroscopy. There have also been reports [198][199][200][201] on the frequencies of the umbrella (out-of-plane or OPLA) Table 11. Fundamental vibrational transition energies (in cm À1 ) of HOO -.…”

“…[197]. f Liu, Gross, and Suits [201]. Yu and Sears [208] 2942 f 1378 f 3108 f 1387 f a The vibrational quanta of the symmetric C-H stretch (a 0 1 ), umbrella (a 00 2 ), anti-symmetric C-H stretch (e 0 ), and deformation (e 0 ), respectively.…”

“…The raw PES was found to overestimate the frequencies of some of the fundamentals by 30 cm À1 and a coordinate scaling was applied to achieve the best overall agreement. The frequencies of Yu and Sears in Table 13 correspond to the scaled PES and experimental frequencies are taken from [195,201].…”

Theoretical Calculations of Infrared Bands of CH3+and CH5+

“…[7][8][9] The information on the quantum mechanical property of CH 3 + was obtained from the previous spectroscopic studies. 5,[10][11][12] Theoretical calculations 13,14 have also reported that the two vibrational states of CH 3 + lie quite close to each other. The determination of vibrational frequencies by computational methods has become increasingly important in many areas in chemistry.…”

First Ultraviolet High-Gain Harmonic-Generation Free-Electron Laser

“…The output exhibits the predicted high stability and a nearly Fourier-transform limited bandwidth. The third-harmonic output at 88 nm accompanying the 266 nm fundamental has already been used in an ion pair imaging experiment [24] in chemical physics as its first user application [25].…”