Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable (2 3S1) 3He and 4He atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasi-unpolarized gas, in the absence of resonant light (T = 1.2 mK): K34(th) = 2.4*10^-10 cm^3/s. This calculation is supported by a measurement of K34 using magneto-optically trapped mixtures containing about 1*10^8 atoms of each species, K34(exp) = 2.5(8)*10^-10 cm^3/s. Theory and experiment show good agreement.Comment: 8 pages, 6 figure

Experimental evidence of a dynamic Jahn-Teller effect in C+60.

Detailed analysis of the highest occupied molecular orbital band shape in the photoelectron spectrum of gaseous C60 reveals a dynamic Jahn-Teller effect in the ground state of C+60. The direct observation of three tunneling states asserts a D3d geometry for the isolated cation, originating from a strong vibronic coupling. These results show that the ionic motion plays an important role in the electron-phonon interaction

Threshold photoelectron spectroscopy in the inner-valence ionization region and photo-double ionization of SF6

The threshold photoelectron (TPE) spectrum of SF6 has been recorded over the photon energy range 25-140 eV using synchrotron radiation and a penetrating-field electron spectrometer. In addition, the photo-double ionization spectrum of SF6 has been obtained over the energy range 30.7-49.3 eV using the threshold photoelectrons coincidence technique. The TPE spectrum in the inner-valence ionization region is found to be significantly different to the conventional photoelectron spectrum in the same binding energy region. Indirect autoionization of neutral Rydberg and shape-resonance states of SF6 dominate the formation of the TPE spectrum. Innervalence SF6+ ion states appear to play a major role in the formation of the SF62+ ion states. The onset of double ionization in SF6 was found to occur at 31.98 ± 0.02 eV

Rotational analysis of the He I photoelectron spectrum of HF

Combined theoretical and experimental studies of He I photoelectron spectra for photoionization of the X^1Σ^+ (v″ = 0) ground state HF leading to the X^2Π (v^+ = 0–2) and A ^2Σ^+ (v^+ = 0–3) ionic states, including detailed analyses of the rotational bandshapes, are reported. Agreement between the measured bandshapes and the calculated spectra, convoluted with the experimental resolution function (22 meV FWHM), is excellent. Ionization potentials of 16.046(1) eV and 19.116(2) eV are obtained for formation of the X and A ionic states, respectively. The vibrational spacings, deduced from the measured data by careful bandshape analysis, are in very good agreement with spectroscopic values