Time-resolved FTIR emission spectroscopy of Au in the 1800 - 4000 cm-1 region: new Rydberg transitions
Abstract
Time-resolved Fourier-transform infrared spectroscopy was applied for observations of the emission arising after irradiation of a Au target with a pulsed nanosecond ArF (λ = 193 nm) laser. A high-repetition-rate laser (1.0 kHz) with an output energy of 15 mJ was focused on a rotating metal target inside a vacuum chamber (average pressure 10−2 Torr).
The infrared emission spectra were observed in the 1800–4000 cm−1 spectral region with a time profile showing maximum emission intensity in 9–11μs after a laser shot. Seven prominent lines are reported; most of them are identified as being due to transitions between low Rydberg nl states of Au with n = 5–10 and l = 0–3.
An alternative identification (6f5/2 → 7d3/2) is given for the 2518.489 cm−1 line previously classified as 8d5/2 → 5f5/2. On the basis of the measured lines, three f levels of the Au atom are reported and revised values are given for six other levels.