Search

We present experimentally measured absolute values of the photoionization cross sections from the 5s5p 1P1 and 5s5p 3P1 excited states of strontium at the first ionization threshold as 11.4±1.8 Mb and 10.7±1.7 Mb respectively using saturated absorption technique along with a thermionic diode ion detector in conjunction with a Nd:YAG pumped dye laser system. These threshold photoionization cross sections values have been utilized to determine the oscillator strengths of the 5s5p 1P1↦5snd 1D2 and 5s5p 3P1↦5snd 3D2 Rydberg transitions. The oscillator strength densities in the continuum corresponding to the 5s5p 3P1 excited state have also been determined by measuring the photoionization cross sections at five ionizing wavelengths above the first ionization threshold. Smooth merging of the discrete f-values into the oscillator strength densities has been observed for the 5s5p 3P1↦5snd 3D2 series across the ionization threshold. [ABSTRACT FROM AUTHOR]

We report new measurements of the oscillator strengths of the 3p 2P3/2 ↦nd 2D5/2, 3/2 and 3p 2P1/2 ↦ nd 2D3/2 Rydberg transitions of sodium using a thermionic diode ion detector in conjunction with the Nd:YAG pumped dye lasers. The ns 2S1/2 and nd 2D5/2,3/2 Rydberg series have been recorded via two-step excitation, from the 3p 2P3/2 and 3p 2P1/2 intermediate states. Employing the saturation technique, the photoionization cross sections from the 3p 2P3/2 and 3p 2P1/2 intermediate states at the first ionization threshold are determined as 7.9(1.3) Mb and 6.7(1.1) Mb respectively. The f-values of the Rydberg transitions are calibrated with the photoionization cross section measured at the first ionization threshold and compared with the earlier data. [ABSTRACT FROM AUTHOR]

We report a systematic line shape analysis study of the 6p7p configuration based 1P1, 3D1 and 3P1 autoionizing resonances in barium using a Nd:YAG pumped dye laser system in conjunction with a thermionic diode ion detector. The even parity isolated autoionizing resonances have been approached via four intermediate states 6 snp 1P1 (6 ≤n ≤8) and 5d6p 1P1. A comparison of the Fano parameters of the resonance profiles reveals that the width of an autoionizing resonance is independent of the excitation path while the line profile parameter changes with the selection of different intermediate states. [ABSTRACT FROM AUTHOR]

The photoionization cross-sections from the 2p2P1/2, 3/2, 3d2D3/2, 5/2 and 3s2S1/2 excited states of lithium have been measured at different ionizing laser wavelengths, above the first ionization threshold. The experiments are performed by using a thermionic diode working in the space charge limited mode and the cross-sections are measured by employing the saturation technique. By changing the ionization photon energy, a smooth frequency dependence of the cross-sections has been observed for the 2p and 3d states. The cross-section from the 3s excited state has been measured at a single photon energy. The measured values of the photoionization cross are compared with the available data. [ABSTRACT FROM AUTHOR]