Rotationally resolved threshold photoelectron spectrum of the methyl radical

Abstract

We report the rotationally resolved, one-photon threshold photoelectron spectrum of the methyl radical, CH3, produced by supersonic-jet, flash pyrolysis. Only rotational transitions with ΔK=0, ±2 are observed and this result is shown to be consistent with photoionization selection rules in D3h symmetry. Assignment of the threshold photoelectron spectrum results in an adiabatic ionization potential of 79 349±3 cm−1.

Rotationally resolved photoionization of polyatomic hydrides: CH3, H2O, H2S, H2CO

“…Methyl radicals were produced by supersonic-jet flash pyrolysis of azomethane, CH 3 NNCH 3 , as described elsewhere. 7 The rotational structure is quite similar to that observed for the bound-bound {3, o+-X bands in CH 3 and CD 3 characterized by aK = 0 electronic transitions with simple p, Q, and R (aN = -1, 0, + 1) branches reminiscent of a diatomic molecule. 37 Due to the similarity of the ground and excited state structures, each branch line is comprised of many closely spaced aK = 0 subbands.…”

“…7 Although H 2 0, H 2 S, and H 2 CO are all planar (C 2v) in their neutral and ionic ground states, the symmetry of the outermost 2h z orbital of formaldehyde and the assignment of its principal axes leads to significant differences in the types of rotational transitions that are observed. Earlier experimental and theoretical work for H 2 0 and HzS are also included to illustrate the dynamical aspects of photoionization of polyatomics as molecular symmetry changes in a group of structurally related systems.…”

Mass resolved MPI spectra of methyl iodide in the 430–490 nm region

“…3. It can be known, in the 430-490 nm region, that three-photon energy agrees with 6p (approximately 58 000-65 000 cm − 1 ) and 7s (lies around 70 000 cm − 1 ) Rydberg states [11,12,[21][22][23][24] of the CH 3 I molecule. Four-photon energy is needed to form the CH 3 I parent ion.…”

Chemical Applications of Zero Kinetic Energy (ZEKE) Photoelectron Spectroscopy

“…The planar methyl radical, isolectronic with NH 3 , was studied by White, Chen et al [114] This effort provided the first rotationally resolved ZEKE measurement of a polyatomic radical. One-photon ionization was achieved by using a tunable VUV laser source.…”