XUV spectroscopy; laser-produced plasmas, ﬂat-ﬁeld spectrograph, Nd : phosphate glass laser.
Absolute measurement for He-𝛼 resonance (1s2 1𝑆0-1s2p 1𝑃1, at 40.2 Å) line emission from a laser-produced carbon plasma has been studied as a function of laser intensity. The optimum laser intensity is found to be ≈ 1.3 × 1012 W/cm2 for the maximum emission of 3.2 × 1013 photons sr-1 pulse-1. Since this line lies in the water window spectral region, it has potential application in x-ray microscopic imaging of biological sample in wet condition. Theoretical calculation using corona model for the emission of this line is also carried out with appropriate ionization and radiative recombination rate coefﬁcients.