D. J. G. Irwin

Energies and lifetimes of excited atomic states in Ar v–Ar viii

The spectra of Ar v–Ar viii have been studied in the wavelength region of 400–1500 A by using beam-foil excitation. Several new transition classifications are proposed in Ar vii and Ar viii. Lifetimes have been measured for 19 excited states in Ar v–Ar viii. The results are compared with previous measurements and with theoretical calculations.

Beam-foil spectroscopy of the Cu I and Zn I isoelectronic sequences☆

Abstract A summary is presented of recent investigations of the Cu I and Zn I isoelectronic sequences. A discussion is given of the 4s4d 1D term, with a provisional energy assignment being made for Se V. Two other Se V terms and five As V terms are also assigned. Lifetimes are presented for the 4p, 4d and 5s levels of the Ge IV, As V and Se VI members of the Cu I sequence, the 4p results being obtained from ANDC analyses using decay curve data the 4s-4p, 4p-5s and 4p-4d transitions. The multiplet ƒ-values derived for the 4s-4p transition are in excellent agreement with theoretical predictions. Lifetimes are also given for the 4s4p 1P0, 4p2 1D2, 4s4d 1D2 and 4s5s 1S0 levels of the Ge III, AS IV and Se V members of the Zn I sequence, the 4s4p 1P0 results again coming from ANDC or constrained-fitting analyses. The agreement with theoretical values here is good up to As IV, but for higher series members the theoretical ƒ-values are significantly higher than the experimental values. Possible reasons for this discrepancy are discussed.

Beam-foil spectroscopy of As III, IV and V

The beam-foil technique is applied to study the spectra of As III-V in the wavelength range 300 to 2000 AA. Fifteen new transitions are assigned to As V, involving the classification of eight new levels. From the 4s, 5s, 6s and 4p, 5p, 6p levels the As V ionisation potential is found to be 62.76+or-0.06 eV. Lifetimes and multiplet f values are reported from transitions from the 4s24d and 4s4p2 2D terms of As III, the 4s5s and 4p2 1S, 4p2 1D, 4s4p1P0 and 4s4d3D terms of As IV, and the 4p2P0, 4d2D and 5s2S terms of As V. Arbitrarily normalised decay curve (ANDC) analyses were used to overcome the problems associated with cascade repopulation in the cases of the 4s4p1P0 (As IV) and 4p2P0 (As V) terms. The resulting multiplet f value for the As V resonance transition is in good agreement with theory, but that for the As IV resonance transition is about 20% below theory, possibly due to omission from the ANDC analysis of the cascade from 4s4d1D, which is yet to be assigned.

Correlated decay curve measurement of the lifetime of the 4p 2P° term in GeIV

Abstract An ANDC analysis of beam-foil decay curves for the 4s-4p, 4p-4d and 4p-5s transitions in Ge IV yield 4p lifetimes 0.91 ± 0.05 ns ( j= 1 2 ) and 0.82±0.05 ns ( j= 3 2 ), and hence a 4s-4p multiplet f value of 0.77 ± 0.05, in excellent agreement with MCHF and RHF (+ core polarization) calculations.