Measurements of the absolute intensities of spectral lines of Kr, Ar, and O ions in the wavelength range of 10 – 18 nm under pulsed laser excitation

Abstract

Abstract We have measured the absolute intensities of the spectral lines of Kr, Ar, and O ions (CO2 gas), which are of interest for reflectometry, microscopy, and lithography in the wavelength range of 10 – 18 nm. We have used pulsed excitation by an Nd : YAG laser with an output wavelength λ = 1064 nm, a pulse energy of 0.8 J, a pulse duration of 5.2 ns and a pulse repetition rate of 10 Hz. The targets are formed during gas outflow through a pulsed supersonic conical nozzle for an inlet gas pressure of 3.5 bar. A spectrometer based on X-ray multilayer mirrors and its calibration procedure are described in detail. The absolute intensities of the spectral lines of Kr IX (λ = 11.5 nm; number of photons: N = 9.3 × 1012 photons pulse−1), Ar VIII (λ = 13.84 nm, N = 3 × 1012 photons pulse−1), and O VI (λ = 12.98 nm, N = 5.17 × 1012 photons pulse−1). The results are compared with the data obtained for Xe ions under the same experimental conditions at the same wavelengths.