XUV Spectra of Ag XVII - Ag XXI and Cd XVIII - Cd XXII from Laser Produced Plasmas

Abstract

The spectra of highly ionized Ag and Cd in the region 20–200 Å excited in laser produced plasmas were recorded and analyzed. The spectral lines identified correspond to Ag XVII - Ag XXI and Cd XVIII -Cd XXII involving transitions of the type 3dk n1 – 3dk nl' and 3dk – 3dk−l nl" where k = 9,10; n = 4,5,6; 1 = s,p,d,f; 1' = s,p,d,f,g, and 1" = p,f.The experimental work was carried out at the Australian National University Research School of Physical Sciences. The Nd=glass laser system delivered pulsed powers of the order of 1015W/cm2 onto flat metalic targets placed in a vacuum. The target could be positioned accurately in the focal plane of the input lens. The spectra were recorded photographically on Kodak SC5 plates with a 2-m grazing incidence spectrograph (Hilger & Watts E-580) employing a 600 lines/mm grating at 88.157° incidence. A maximum of three laser pulses gave the desired plate exposure while a single shot exposure from a pure carbon target plasma provided the reference points for wavelength calibration. The well-known Lyman spectra of CVI and CV appeared strong and could be clearly identified upto their 5th order. The wavelengths of some strong lines of Ag XIX and Cd XX previously measured (1) were used as secondary wavelength standards and a best fit was then made with the wavelengths computed from the dispersion equation of the grating. The accuracy of the measured wavelengths was within 0.02A° and better than 0.005A° at points closer to the reference lines.