Using resonant two-photon ionization of metastable rare gas atoms Rg(mp 5(m + 1)s 3P2,0) in a collimated beam by two transverse cw dye lasers, we have performed a comprehensive high resolution study of the odd Rg(ns',J =0,1) autoionization resonances of all the heavier rare gases Rg--Ne, Ar, Kr and Xe. In this way, we have determined the variation of the nearly n-independent reduced resonance widths F, = n*3. Fn (n*= effective quantum number) with atomic size andfor the first time -with the angular momentum J for all Rg. The reduced widths for the Rg(ns', J = 1) resonances vary by about a factor of three, being lowest for Ne(371 cm -1) and largest for Kr(l185 cm-1). Compared to J = 1, the Rg(ns', J =0) resonances are three times narrower for Ne, but up to two times broader for Ar, Kr, and Xe. The results of ab initio calculations for the widths are reported, in which the relevant transition matrix elements are carefully evaluated. Good overall agreement of the calculated widths with the experimental data is achieved. For Rg(ns', J = 0), the first order s'-d coupling amplitude provides a satisfactory description only for Rg = Ne, whereas for Rg = Ar-Xe, correlation effects are important. For Rg(ns', J = 1), the additional amplitudes due to s'-d exchange coupling and due to s'-s decay are found to be of varying importance with atomic number. Destructive interference between the different amplitudes and the influence of Rg(ns', J = i)-Rg(nd', J --t) coupling are responsible for the fact that the (ns', J = 1) resonances are narrower than the (ns', J = 0) resonances for Ar, Kr, and Xe.

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An electron spectrometric study has been performed on HC1 using metastable helium and neon atoms as well as neon resonance photons. High resolution electron spectra were obtained with two different beam apparatuses for a mixed He(2 ~S, 23S) beam, a pure He(23S) beam, and, for the first time, state-selected pure Ne(3s3P2) and pure Ne(3s3P0) beams, and for NeI resonance photons. For the system He(23S)+HC1 the vibrational populations P(v') of the formed HCI+(X2//i, v') and HCI+(A 2L'+, v') ions are found to differ from the Franck-Condon factors for unperturbed potentials, indicating slight bond stretching in HC1 upon He(2 3S) approach. For He(21S) + HC1 the vibrational peak shapes and vibrational populations are substantially different from the He(2aS) case, pointing to an additional, charge exchanged interaction (He ÷ +HC1-) in the entrance channel of the former system. For the first time, we have detected the electrons in both the He(21S) + HC1 and He(2 3S) + HC1 spectra associated with the major mechanism for the formation of C1 ÷ ions: energy transfer to repulsive HCI** Rydberg states, dissociating to H(1 s) and autoionizing Ct**(1D2 n/) atoms. For both Ne (3P2)+ HC1 and Ne(3Po)+HC1, the populations P(v') of both final molecular states HCI+(X, A) agree closely with the Franck-Condon factors at the average relative collision energy E~oll = 55 meV and, for HCt + (A 2S+), also at E~o n = 130 meV.

Using resonant two-photon excitation of a metastable Ne(Zp'3s 'Pod beam by two singlemode cw dye lasers, we have measured reduced widths T,=n"T. for the four Ne(Zp'(2Pp,,,) nd' [Kl,) autoionidngresonance series (IKl,=[!l:, [$I2,[;l2, and If],). The resulting values are r.= l67(7), 350(7), 87(2), and 73(3) m?, respectively, in good agreement with predictions by a semiempirical multichannel quantum-defect analysis involving complex quantum defects.

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