A vacuum ultraviolet laser single-photon zero kinetic energy photoelectron spectroscopic study of the [X.sup.2][E.sub.3/2] ground electronic state of C[H.sub.3][Br.sup.+]

The vacuum ultraviolet laser single-photon zero kinetic energy (ZEKE) photoelectron spectrum of the [X.sup.2][E.sub.3/2] ground electronic state of the methyl bromide cation is reported. The spectrum is dominated by the origin hand [0.sup.0.sub.0] of the transition [X.sup.2][E.sub.3/2] [left arrow] [X.sup.1][A.sub.1]. In addition, the [2.sup.1.sub.0] band and the [3.sup.1.sub.1] hot band are observed. All observed bands show similar rotational contours. Simulation of the rotational contour of the origin band yields the first ionization energy of methyl bromide (85 031.2 [+ or -] 1.0 [cm.sup.-1]) and the rotational constants of the cation in its ground electronic state. Key words: methyl bromide, vacuum ultraviolet laser, single-photon excitation, zero kinetic energy photoelectron spectroscopy.