Electron spectroscopy of hydrogen chloride from 5 to 19 eV

Abstract

Using an electron energy loss spectrometer, we have measured the spectra of electrons inelastically scattered from HCl for an incident electron energy of 200 eV, energy loss between 5 and 19 eV, and scattering angles of 0° to 19°. The low-angle scattering spectra, corresponding to photoabsorption, confirm many optically allowed energy levels in HCl, and locate many others, including six levels of the σ2 π3 nsσ 1Π Rydberg series. Series analysis yields an HCl ionization potential of 12.790 eV, midway between the known HCl+ 2Π3/2, 1/2 energies 12.750 and 12.830 eV. In the ionization continuum, we locate a new vibrational progression associated with previously observed (negative ion) Feshbach resonances, which has configuration 3pσ3pπ4 4sσ, and is the lowest Rydberg state associated with the first excited ionic state A 2Σ+.