One- and two-photon detachment ofO−

Abstract

Cross sections for one-and two-photon detachment of O − (1s 2 2s 2 2p 5 2 P o ) have been determined in a joint experimental and theoretical study. The absolute measurement is based on the animatedcrossed-beam technique, which is extended to the case of pulsed lasers, pulsed ion beams and multiphoton detachment. The ab initio calculations employ R-matrix Floquet theory, with simple descriptions of the initial bound state and the residual oxygen atom which reproduce well the electron affinity and ground state polarizability. For one photon detachment, the measured and computed cross sections are in good mutual agreement, departing significantly from previous reference experiments and calculations. The generalized two-photon detachment cross section, measured at the Nd:YAG laser wavelength, is in good agreement with the R-matrix Floquet calculations. Long-standing discrepancies between theory and experiment are thus resolved.

Absolute cross sections and asymmetry parameters for photodetachment of C−(4So)

“…The carbon anion exists in two bound states: the ground state C − (1s 2 2s 2 2p 3 4 S o ), which has an affinity of 1.2621226 (11) eV with respect to the C(1s 2 2s 2 2p 2 3 P 0 ) ground level [5], and an excited state C − (1s 2 2s 2 2p 3 2 D o ) which is very weakly bound by about 33 meV [6]. In this work, we consider only photodetachment from the 4 for the pulse starting at t = t p,Z is formally given by 152 ρ p (x, y, z, t; Z) = ρ(x, y, z; t p,Z )…”