Pulsed-ramped-field-ionization zero-kinetic-energy photoelectron spectroscopy: a methodological advance.

A new experimental method has been developed to record photoelectron spectra based on the well-established pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopy technique and inspired by the data treatment employed in slow photoelectron spectroscopy. This method has been successfully applied to two well-known systems: the X+2Πg,1/2(v+ = 0) ← X1Σ+g(v = 0) and the X+1Σ+(v+ = 2) ← X2Π1/2(v = 0) ionizing transitions of CO2 and NO, respectively. The first results highlight several advantages of our technique such as an improved signal-to-noise ratio without degrading the spectral resolution and a direct field-free energy determination. The data obtained for NO indicate that this method might be useful for studying field-induced autoionization processes.