Time-resolved Fourier-transform infrared emission spectroscopy of Au in the 1800-4000-cm(-1) region: Rydberg transitions

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 (lambda = 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 -11 mu s 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 (6f(5/2) -> 7d(3/2)) is given for the 2518.489 cm(-1) line previously classified as 8d(5/2) -> 5f(5/2). 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.